Citrine Quartz
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Quartz is a hard,
crystalline A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macrosc ...
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
composed of silica (
silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
). The atoms are linked in a continuous framework of SiO4 silicon-oxygen
tetrahedra In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the o ...
, with each oxygen being shared between two tetrahedra, giving an overall
chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
of SiO2. Quartz is the second most abundant
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
in
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
's
continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ...
, behind
feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldsp ...
. Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are
chiral Chirality is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable from ...
. The transformation from α-quartz to β-quartz takes place abruptly at . Since the transformation is accompanied by a significant change in volume, it can easily induce microfracturing of ceramics or rocks passing through this temperature threshold. There are many different varieties of quartz, several of which are classified as
gemstone A gemstone (also called a fine gem, jewel, precious stone, or semiprecious stone) is a piece of mineral crystal which, in cut and polished form, is used to make jewelry or other adornments. However, certain rocks (such as lapis lazuli, opal, ...
s. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of
jewelry Jewellery ( UK) or jewelry (U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a western ...
and
hardstone carving Hardstone carving is a general term in art history and archaeology for the artistic carving of predominantly semi-precious stones (but also of gemstones), such as jade, rock crystal (clear quartz), agate, onyx, jasper, serpentinite, or carnelian, ...
s, especially in
Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...
. Quartz is the
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
defining the value of 7 on the
Mohs scale of hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...
, a qualitative scratch method for determining the hardness of a material to abrasion.


Etymology

The word "quartz" is derived from the
German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
word "Quarz", which had the same form in the first half of the 14th century in
Middle High German Middle High German (MHG; german: Mittelhochdeutsch (Mhd.)) is the term for the form of German spoken in the High Middle Ages. It is conventionally dated between 1050 and 1350, developing from Old High German and into Early New High German. High ...
and in
East Central German East Central German or East Middle German (german: Ostmitteldeutsch) is the eastern non- Franconian Central German language and is part of High German. Present-day Standard German as a High German variant, has actually developed from a compromi ...
and which came from the
Polish Polish may refer to: * Anything from or related to Poland, a country in Europe * Polish language * Poles Poles,, ; singular masculine: ''Polak'', singular feminine: ''Polka'' or Polish people, are a West Slavic nation and ethnic group, w ...
dialect term ''kwardy'', which corresponds to the
Czech Czech may refer to: * Anything from or related to the Czech Republic, a country in Europe ** Czech language ** Czechs, the people of the area ** Czech culture ** Czech cuisine * One of three mythical brothers, Lech, Czech, and Rus' Places * Czech, ...
term ''tvrdý'' ("hard"). The
Ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cultu ...
referred to quartz as κρύσταλλος (''krustallos'') derived from the
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
''κρύος'' (''kruos'') meaning "icy cold", because some
philosopher A philosopher is a person who practices or investigates philosophy. The term ''philosopher'' comes from the grc, φιλόσοφος, , translit=philosophos, meaning 'lover of wisdom'. The coining of the term has been attributed to the Greek th ...
s (including
Theophrastus Theophrastus (; grc-gre, Θεόφραστος ; c. 371c. 287 BC), a Greek philosopher and the successor to Aristotle in the Peripatetic school. He was a native of Eresos in Lesbos.Gavin Hardy and Laurence Totelin, ''Ancient Botany'', Routledge ...
) apparently believed the mineral to be a form of supercooled ice. Today, the term ''
rock crystal Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...
'' is sometimes used as an alternative name for transparent coarsely crystalline quartz.


Crystal habit and structure

Quartz belongs to the
trigonal crystal system In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crystal ...
at room temperature, and to the
hexagonal crystal system In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crysta ...
above . The ideal crystal shape is a six-sided
prism Prism usually refers to: * Prism (optics), a transparent optical component with flat surfaces that refract light * Prism (geometry), a kind of polyhedron Prism may also refer to: Science and mathematics * Prism (geology), a type of sedimentary ...
terminating with six-sided
pyramid A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilat ...
s at each end. In
nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...
quartz crystals are often twinned (with twin right-handed and left-handed quartz crystals), distorted, or so intergrown with adjacent crystals of quartz or other minerals as to only show part of this shape, or to lack obvious crystal faces altogether and appear massive. Well-formed crystals typically form as a druse (a layer of crystals lining a void), of which quartz
geode A geode (; ) is a geological secondary formation within sedimentary and volcanic rocks. Geodes are hollow, vaguely spherical rocks, in which masses of mineral matter (which may include crystals) are secluded. The crystals are formed by the fill ...
s are particularly fine examples. The crystals are attached at one end to the enclosing rock, and only one termination pyramid is present. However, doubly terminated crystals do occur where they develop freely without attachment, for instance, within
gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...
. α-quartz crystallizes in the trigonal crystal system,
space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchan ...
''P''3121 or ''P''3221 (space group 152 or 154 resp.) depending on the chirality. Above , α-quartz in ''P''3121 becomes the more symmetric hexagonal ''P''6422 (space group 181), and α-quartz in ''P''3221 goes to space group ''P''6222 (no. 180). These space groups are truly chiral (they each belong to the 11 enantiomorphous pairs). Both α-quartz and β-quartz are examples of chiral crystal structures composed of achiral building blocks (SiO4 tetrahedra in the present case). The transformation between α- and β-quartz only involves a comparatively minor rotation of the tetrahedra with respect to one another, without a change in the way they are linked. However, there is a significant change in volume during this transition, and this can result in significant microfracturing in ceramics and in rocks of the Earth's crust. File:Α-Quartz.svg, Crystal structure of α-quartz (red balls are oxygen, grey are silicon) File:Β-Quartz.svg, β-quartz


Varieties (according to microstructure)

Although many of the varietal names historically arose from the color of the mineral, current scientific naming schemes refer primarily to the microstructure of the mineral. Color is a secondary identifier for the cryptocrystalline minerals, although it is a primary identifier for the macrocrystalline varieties.


Varieties (according to color)

Pure quartz, traditionally called rock crystal or clear quartz, is colorless and
transparent Transparency, transparence or transparent most often refer to: * Transparency (optics), the physical property of allowing the transmission of light through a material They may also refer to: Literal uses * Transparency (photography), a still, ...
or translucent, and has often been used for
hardstone carving Hardstone carving is a general term in art history and archaeology for the artistic carving of predominantly semi-precious stones (but also of gemstones), such as jade, rock crystal (clear quartz), agate, onyx, jasper, serpentinite, or carnelian, ...
s, such as the
Lothair Crystal The Lothair Crystal (also known as the Lothar Crystal or the Susanna Crystal) is an engraved gem from Lotharingia in northwest Europe, showing scenes of the biblical story of Susanna, dating from 855–869. The Lothair Crystal is an object in t ...
. Common colored varieties include citrine, rose quartz, amethyst, smoky quartz, milky quartz, and others. These color differentiations arise from the presence of impurities which change the molecular orbitals, causing some electronic transitions to take place in the visible spectrum causing colors. The most important distinction between types of quartz is that of ''macrocrystalline'' (individual crystals visible to the unaided eye) and the
microcrystalline A microcrystalline material is a crystallized substance or rock that contains small crystals visible only through microscopic examination. There is little agreement on the range of crystal sizes that should be regarded as microcrystalline, but th ...
or
cryptocrystalline Cryptocrystalline is a rock microstructure, rock texture made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically in thin section by transmitted polarized light. Among the sedimentary rocks, chert a ...
varieties ( aggregates of crystals visible only under high magnification). The cryptocrystalline varieties are either translucent or mostly opaque, while the transparent varieties tend to be macrocrystalline.
Chalcedony Chalcedony ( , or ) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. ...
is a cryptocrystalline form of
silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...
consisting of fine intergrowths of both quartz, and its
monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...
polymorph moganite. Other opaque gemstone varieties of quartz, or mixed rocks including quartz, often including contrasting bands or patterns of color, are
agate Agate () is a common rock formation, consisting of chalcedony and quartz as its primary components, with a wide variety of colors. Agates are primarily formed within volcanic and metamorphic rocks. The ornamental use of agate was common in Ancie ...
,
carnelian Carnelian (also spelled cornelian) is a brownish-red mineral commonly used as a semi-precious gemstone. Similar to carnelian is sard, which is generally harder and darker (the difference is not rigidly defined, and the two names are often use ...
or sard,
onyx Onyx primarily refers to the parallel banded variety of chalcedony, a silicate mineral. Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands: agate has curved bands and onyx has parallel bands. The c ...
, heliotrope, and
jasper Jasper, an aggregate of microgranular quartz and/or cryptocrystalline chalcedony and other mineral phases,Kostov, R. I. 2010. Review on the mineralogical systematics of jasper and related rocks. – Archaeometry Workshop, 7, 3, 209-213PDF/ref> ...
.


Amethyst

Amethyst Amethyst is a violet variety of quartz. The name comes from the Koine Greek αμέθυστος ''amethystos'' from α- ''a-'', "not" and μεθύσκω (Ancient Greek) / μεθώ (Modern Greek), "intoxicate", a reference to the belief that t ...
is a form of quartz that ranges from a bright vivid violet to a dark or dull lavender shade. The world's largest deposits of amethysts can be found in Brazil, Mexico, Uruguay, Russia, France, Namibia, and Morocco. Sometimes amethyst and citrine are found growing in the same crystal. It is then referred to as
ametrine Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mixture of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrine is m ...
. Amethyst derives its color from traces of iron in its structure.


Blue quartz

Blue quartz contains inclusions of fibrous magnesio-riebeckite or
crocidolite Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2. It forms a solid solution series with magnesioriebeckite. It crystallizes in the monoclinic system, usually as long prisma ...
.


Dumortierite quartz

Inclusions of the mineral
dumortierite Dumortierite is a fibrous variably colored aluminium boro-silicate mineral, Al7BO3(SiO4)3O3. Dumortierite crystallizes in the orthorhombic system typically forming fibrous aggregates of slender prismatic crystals. The crystals are vitreous and var ...
within quartz pieces often result in silky-appearing splotches with a
blue Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when obs ...
hue. Shades of
purple Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters, pu ...
or
grey Grey (more common in British English) or gray (more common in American English) is an intermediate color between black and white. It is a neutral or achromatic color, meaning literally that it is "without color", because it can be composed o ...
sometimes also are present. "Dumortierite quartz" (sometimes called "blue quartz") will sometimes feature contrasting light and dark color zones across the material. "Blue quartz" is a minor gemstone.


Citrine

Citrine is a variety of quartz whose color ranges from pale yellow to brown due to a submicroscopic distribution of colloidal
ferric In chemistry, iron(III) refers to the element iron in its +3 oxidation state. In ionic compounds (salts), such an atom may occur as a separate cation (positive ion) denoted by Fe3+. The adjective ferric or the prefix ferri- is often used to spe ...
hydroxide impurities. Natural citrines are rare; most commercial citrines are heat-treated
amethyst Amethyst is a violet variety of quartz. The name comes from the Koine Greek αμέθυστος ''amethystos'' from α- ''a-'', "not" and μεθύσκω (Ancient Greek) / μεθώ (Modern Greek), "intoxicate", a reference to the belief that t ...
s or
smoky quartz Smoky quartz is a brownish grey, translucent variety of quartz that ranges in clarity from almost complete transparency to an almost-opaque brownish-gray or black crystals. The smoky color results from free silicon formed from the silicon dioxide ...
es. However, a heat-treated amethyst will have small lines in the crystal, as opposed to a natural citrine's cloudy or smoky appearance. It is nearly impossible to differentiate between cut citrine and yellow
topaz Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al Si O( F, OH). It is used as a gemstone in jewelry and other adornments. Common topaz in its natural state is colorless, though trace element impurities can mak ...
visually, but they differ in
hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...
. Brazil is the leading producer of citrine, with much of its production coming from the state of
Rio Grande do Sul Rio Grande do Sul (, , ; "Great River of the South") is a Federative units of Brazil, state in the South Region, Brazil, southern region of Brazil. It is the Federative_units_of_Brazil#List, fifth-most-populous state and the List of Brazilian st ...
. The name is derived from the Latin word ''citrina'' which means "yellow" and is also the origin of the word "
citron The citron (''Citrus medica''), historically cedrate, is a large fragrant citrus fruit with a thick rind. It is said to resemble a 'huge, rough lemon'. It is one of the original citrus fruits from which all other citrus types developed throu ...
". Sometimes citrine and amethyst can be found together in the same crystal, which is then referred to as
ametrine Ametrine, also known as trystine or by its trade name as bolivianite, is a naturally occurring variety of quartz. It is a mixture of amethyst and citrine with zones of purple and yellow or orange. Almost all commercially available ametrine is m ...
. Citrine has been referred to as the "merchant's stone" or "money stone", due to a superstition that it would bring prosperity. Citrine was first appreciated as a golden-yellow gemstone in Greece between 300 and 150 BC, during the Hellenistic Age. Yellow quartz was used prior to that to decorate jewelry and tools but it was not highly sought after.


Milky quartz

Milk quartz or milky quartz is the most common variety of crystalline quartz. The white color is caused by minute
fluid inclusions image:Inclumed.gif, 250px, Trapped in a time capsule the same size as the diameter of a human hair, the ore-forming liquid in this inclusion was so hot and contained so much dissolved solids that when it cooled, crystals of halite, sylvite, gypsum, ...
of gas, liquid, or both, trapped during crystal formation, making it of little value for optical and quality gemstone applications.


Rose quartz

Rose quartz is a type of quartz that exhibits a pale pink to rose red hue. The color is usually considered as due to trace amounts of
titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...
,
iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...
, or
manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
, in the material. Some rose quartz contain microscopic
rutile Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer Polymorphism (materials science), polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest ...
needles that produce asterism in transmitted light. Recent
X-ray diffraction X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...
studies suggest that the color is due to thin microscopic fibers of possibly
dumortierite Dumortierite is a fibrous variably colored aluminium boro-silicate mineral, Al7BO3(SiO4)3O3. Dumortierite crystallizes in the orthorhombic system typically forming fibrous aggregates of slender prismatic crystals. The crystals are vitreous and var ...
within the quartz. Additionally, there is a rare type of pink quartz (also frequently called crystalline rose quartz) with color that is thought to be caused by trace amounts of
phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...
or
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...
. The color in crystals is apparently photosensitive and subject to fading. The first crystals were found in a
pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...
found near Rumford,
Maine Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and north ...
, US and in
Minas Gerais Minas Gerais () is a state in Southeastern Brazil. It ranks as the second most populous, the third by gross domestic product (GDP), and the fourth largest by area in the country. The state's capital and largest city, Belo Horizonte (literally ...
,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
.


Smoky quartz

Smoky quartz Smoky quartz is a brownish grey, translucent variety of quartz that ranges in clarity from almost complete transparency to an almost-opaque brownish-gray or black crystals. The smoky color results from free silicon formed from the silicon dioxide ...
is a gray, translucent version of quartz. It ranges in clarity from almost complete transparency to a brownish-gray crystal that is almost opaque. Some can also be black. The translucency results from natural irradiation acting on minute traces of aluminum in the crystal structure.


Prasiolite

Prasiolite Prasiolite (also known as green quartz, green amethyst or vermarine) is a green variety of quartz. Since 1950, almost all natural prasiolite has come from a small Brazilian mine, but it has also been mined in the Lower Silesia region of Polan ...
, also known as ''vermarine'', is a variety of quartz that is green in color. Since 1950, almost all natural prasiolite has come from a small
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
ian mine, but it is also seen in
Lower Silesia Lower Silesia ( pl, Dolny Śląsk; cz, Dolní Slezsko; german: Niederschlesien; szl, Dolny Ślōnsk; hsb, Delnja Šleska; dsb, Dolna Šlazyńska; Silesian German: ''Niederschläsing''; la, Silesia Inferior) is the northwestern part of the ...
in
Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...
. Naturally occurring prasiolite is also found in the
Thunder Bay Thunder Bay is a city in and the seat of Thunder Bay District, Ontario, Canada. It is the most populous municipality in Northwestern Ontario and the second most populous (after Greater Sudbury) municipality in Northern Ontario; its population ...
area of
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
. It is a rare mineral in nature; most green quartz is heat-treated amethyst.


Synthetic and artificial treatments

Not all varieties of quartz are naturally occurring. Some clear quartz crystals can be treated using heat or gamma-irradiation to induce color where it would not otherwise have occurred naturally. Susceptibility to such treatments depends on the location from which the quartz was mined.
Prasiolite Prasiolite (also known as green quartz, green amethyst or vermarine) is a green variety of quartz. Since 1950, almost all natural prasiolite has come from a small Brazilian mine, but it has also been mined in the Lower Silesia region of Polan ...
, an olive colored material, is produced by heat treatment; natural prasiolite has also been observed in Lower Silesia in Poland. Although citrine occurs naturally, the majority is the result of heat-treating amethyst or smoky quartz.
Carnelian Carnelian (also spelled cornelian) is a brownish-red mineral commonly used as a semi-precious gemstone. Similar to carnelian is sard, which is generally harder and darker (the difference is not rigidly defined, and the two names are often use ...
has been heat-treated to deepen its color since prehistoric times. Because natural quartz is often twinned, synthetic quartz is produced for use in industry. Large, flawless, single crystals are synthesized in an
autoclave An autoclave is a machine used to carry out industrial and scientific processes requiring elevated temperature and pressure in relation to ambient pressure and/or temperature. Autoclaves are used before surgical procedures to perform sterilizat ...
via the hydrothermal process. Like other crystals, quartz may be coated with metal vapors to give it an attractive sheen.


Occurrence

Quartz is a defining constituent of
granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
and other
felsic In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted with mafic rocks, whi ...
igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...
s. It is very common in
sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
s such as
sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...
and
shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...
. It is a common constituent of
schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes o ...
,
gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...
,
quartzite Quartzite is a hard, non- foliated metamorphic rock which was originally pure quartz sandstone.Essentials of Geology, 3rd Edition, Stephen Marshak, p 182 Sandstone is converted into quartzite through heating and pressure usually related to tect ...
and other
metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...
s. Quartz has the lowest potential for
weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...
in the
Goldich dissolution series The Goldich dissolution series is a method of predicting the relative stability or weathering rate of common igneous minerals on the Earth's surface, with minerals that form at higher temperatures and pressures less stable on the surface than minera ...
and consequently it is very common as a residual mineral in stream sediments and residual
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
s. Generally a high presence of quartz suggests a " mature" rock, since it indicates the rock has been heavily reworked and quartz was the primary mineral that endured heavy weathering. While the majority of quartz crystallizes from molten
magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...
, quartz also chemically precipitates from hot
hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...
veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...
as
gangue In mining, gangue () is the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. It is thus distinct from overburden, which is the waste rock or materials overlying an ore or mineral body t ...
, sometimes with
ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...
minerals like gold, silver and copper. Large crystals of quartz are found in magmatic
pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...
s. Well-formed crystals may reach several meters in length and weigh hundreds of kilograms. Elemental impurity incorporation strongly influences the ability to process and utilize quartz. Naturally occurring quartz crystals of extremely high purity, necessary for the crucibles and other equipment used for growing
silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...
wafers A wafer is a crisp, often sweet, very thin, flat, light and dry biscuit, often used to decorate ice cream, and also used as a garnish on some sweet dishes. Wafers can also be made into cookies with cream flavoring sandwiched between them. They ...
in the
semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...
industry, are expensive and rare. These high-purity quartz are defined containing less than 50 ppm of impurity elements. A major mining location for high purity quartz is the Spruce Pine Gem Mine in Spruce Pine, North Carolina,
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
. Quartz may also be found in
Caldoveiro Peak Caldoveiro Peak (Pico Caldoveiro) is a protected mountain range in Asturias, Northern Spain, with a maximum peak of 1,357 meters, near the village of Villabre. It spans the parishes of Yernes, Proaza, Tameza, Grau (Grado), and Teberga (Teve ...
, in
Asturias Asturias (, ; ast, Asturies ), officially the Principality of Asturias ( es, Principado de Asturias; ast, Principáu d'Asturies; Galician-Asturian: ''Principao d'Asturias''), is an autonomous communities of Spain, autonomous community in nor ...
,
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...
. The largest documented single crystal of quartz was found near Itapore, Goiaz, Brazil; it measured approximately 6.1×1.5×1.5 m and weighed 39,916
kilogram The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially ...
s.


Mining

Quartz is extracted from
open pit mines Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique of extracting rock (geology), rock or minerals from the earth from an open-air pit, sometimes known as a Borrow pit, b ...
. Miners occasionally use explosives to expose deep pockets of quartz. More frequently,
bulldozer A bulldozer or dozer (also called a crawler) is a large, motorized machine equipped with a metal blade to the front for pushing material: soil, sand, snow, rubble, or rock during construction work. It travels most commonly on continuous track ...
s and
backhoe A backhoe—also called rear actor or back actor—is a type of excavating equipment, or digger, consisting of a digging bucket on the end of a two-part articulated arm. It is typically mounted on the back of a tractor or front loader, the latt ...
s are used to remove soil and clay and expose quartz veins, which are then worked using hand tools. Care must be taken to avoid sudden temperature changes that may damage the crystals. Almost all the industrial demand for quartz crystal (used primarily in electronics) is met with synthetic quartz produced by the hydrothermal process. However, synthetic crystals are less prized for use as gemstones. The popularity of
crystal healing Crystal healing is a pseudoscientific alternative-medicine practice that uses semiprecious stones and crystals such as quartz, agate, amethyst or opal. Adherents of the practice claim that these have healing powers, but there is no scientific ...
has increased the demand for natural quartz crystals, which are now often mined in
developing countries A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
using primitive mining methods, sometimes involving
child labor Child labour refers to the exploitation of children through any form of work that deprives children of their childhood, interferes with their ability to attend regular school, and is mentally, physically, socially and morally harmful. Such e ...
.


Related silica minerals

Tridymite Tridymite is a high-temperature polymorph of silica and usually occurs as minute tabular white or colorless pseudo-hexagonal crystals, or scales, in cavities in felsic volcanic rocks. Its chemical formula is Si O2. Tridymite was first described ...
and
cristobalite Cristobalite is a mineral polymorph of silica that is formed at very high temperatures. It has the same chemical formula as quartz, SiO2, but a distinct crystal structure. Both quartz and cristobalite are polymorphs with all the members of the ...
are high-temperature polymorphs of SiO2 that occur in high-silica
volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...
rocks.
Coesite Coesite is a form ( polymorph) of silicon dioxide Si O2 that is formed when very high pressure (2–3 gigapascals), and moderately high temperature (), are applied to quartz. Coesite was first synthesized by Loring Coes Jr., a chemist at the ...
is a denser polymorph of SiO2 found in some meteorite impact sites and in metamorphic rocks formed at pressures greater than those typical of the Earth's crust. Stishovite is a yet denser and higher-pressure polymorph of SiO2 found in some meteorite impact sites.
Lechatelierite Lechatelierite is silica glass, amorphous SiO2, non-crystalline mineraloid. Structure Lechatelierite is a mineraloid as it does not have a crystal structure. Although not a true mineral, it is often classified in the quartz mineral group. Formati ...
is an
amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek ''a'' ("wi ...
silica
glass Glass is a non-crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of ...
SiO2 which is formed by
lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
strikes in quartz
sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...
.


Safety

As quartz is a form of silica, it is a possible cause for concern in various workplaces. Cutting, grinding, chipping, sanding, drilling, and polishing natural and manufactured stone products can release hazardous levels of very small, crystalline silica dust particles into the air that workers breathe. Crystalline silica of respirable size is a recognized human
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
and may lead to other diseases of the lungs such as
silicosis Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust. It is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis. Silicos ...
and
pulmonary fibrosis Pulmonary fibrosis is a condition in which the lungs become scarred over time. Symptoms include shortness of breath, a dry cough, feeling tired, weight loss, and nail clubbing. Complications may include pulmonary hypertension, respiratory failu ...
.


History

The word "quartz" comes from the
German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
, which is of Slavic origin (Czech miners called it ''křemen''). Other sources attribute the word's origin to the
Saxon The Saxons ( la, Saxones, german: Sachsen, ang, Seaxan, osx, Sahson, nds, Sassen, nl, Saksen) were a group of Germanic * * * * peoples whose name was given in the early Middle Ages to a large country (Old Saxony, la, Saxonia) near the Nor ...
word ''Querkluftertz'', meaning ''cross-vein ore''. Quartz is the most common material identified as the mystical substance
maban Maban, mabain or mabanba is a material that is held to be magical in Australian Aboriginal mythology. It is the material from which the shamans and elders of indigenous Australia supposedly derive their magical powers. Among the Ngaanyatjarra pe ...
in
Australian Aboriginal mythology Australian Aboriginal religion and mythology is the sacred spirituality represented in the stories performed by Aboriginal Australians within each of the Aboriginal Australian languages, language groups across Australia in their Aboriginal ce ...
. It is found regularly in passage tomb cemeteries in Europe in a burial context, such as
Newgrange Newgrange ( ga, Sí an Bhrú) is a prehistoric monument in County Meath in Ireland, located on a rise overlooking the River Boyne, west of Drogheda. It is an exceptionally grand passage tomb built during the Neolithic Period, around 3200 BC, ...
or
Carrowmore Carrowmore ( ga, An Cheathrú Mhór, 'the great quarter') is a large group of megalithic monuments on the Coolera Peninsula to the west of Sligo, Ireland. They were built in the 4th millennium BC, during the Neolithic (New Stone Age). There ...
in
Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...
. The
Irish Irish may refer to: Common meanings * Someone or something of, from, or related to: ** Ireland, an island situated off the north-western coast of continental Europe ***Éire, Irish language name for the isle ** Northern Ireland, a constituent unit ...
word for quartz is ''grianchloch'', which means 'sunstone'. Quartz was also used in
Prehistoric Ireland The prehistory of Ireland has been pieced together from archaeological evidence, which has grown at an increasing rate over the last decades. It begins with the first evidence of permanent human residence in Ireland around 10,500 BC (although ...
, as well as many other countries, for
stone tool A stone tool is, in the most general sense, any tool made either partially or entirely out of stone. Although stone tool-dependent societies and cultures still exist today, most stone tools are associated with prehistoric (particularly Stone Ag ...
s; both vein quartz and rock crystal were
knapped Knapping is the shaping of flint, chert, obsidian, or other conchoidal fracturing stone through the process of lithic reduction to manufacture stone tools, strikers for flintlock firearms, or to produce flat-faced stones for building or facing w ...
as part of the
lithic technology In archaeology, lithic technology includes a broad array of techniques used to produce usable tools from various types of stone. The earliest stone tools were recovered from modern Ethiopia and were dated to between two-million and three-million ...
of the prehistoric peoples. While
jade Jade is a mineral used as jewellery or for ornaments. It is typically green, although may be yellow or white. Jade can refer to either of two different silicate minerals: nephrite (a silicate of calcium and magnesium in the amphibole group of ...
has been since earliest times the most prized semi-precious stone for carving in
East Asia East Asia is the eastern region of Asia, which is defined in both geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea and ...
and
Pre-Columbian In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, th ...
America, in Europe and the Middle East the different varieties of quartz were the most commonly used for the various types of
jewelry Jewellery ( UK) or jewelry (U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a western ...
and
hardstone carving Hardstone carving is a general term in art history and archaeology for the artistic carving of predominantly semi-precious stones (but also of gemstones), such as jade, rock crystal (clear quartz), agate, onyx, jasper, serpentinite, or carnelian, ...
, including
engraved gem An engraved gem, frequently referred to as an intaglio, is a small and usually semi-precious gemstone that has been carved, in the Western tradition normally with images or inscriptions only on one face. The engraving of gemstones was a major lu ...
s and cameo gems,
rock crystal vase A rock crystal vase is a vase made of rock crystal, a type of hardstone carving. Such vases were rare, expensive, and decorated with gold and jewels, used by royalty in Europe. A rock crystal vase that probably originated in the seventh century ...
s, and extravagant vessels. The tradition continued to produce objects that were very highly valued until the mid-19th century, when it largely fell from fashion except in jewelry. Cameo technique exploits the bands of color in onyx and other varieties. Roman naturalist
Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic '' ...
believed quartz to be water
ice Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...
, permanently frozen after great lengths of time. (The word "crystal" comes from the Greek word ''κρύσταλλος'', "ice".) He supported this idea by saying that quartz is found near glaciers in the Alps, but not on volcanic mountains, and that large quartz crystals were fashioned into spheres to cool the hands. This idea persisted until at least the 17th century. He also knew of the ability of quartz to split light into a
spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors i ...
. In the 17th century,
Nicolas Steno Niels Steensen ( da, Niels Steensen; Latinized to ''Nicolaus Steno'' or ''Nicolaus Stenonius''; 1 January 1638 – 25 November 1686crystallography Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids. Crystallography is a fundamental subject in the fields of materials science and solid-state physics (condensed matter physics). The wor ...
. He discovered that regardless of a quartz crystal's size or shape, its long prism faces always joined at a perfect 60° angle. Quartz's
piezoelectric Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied Stress (mechanics), mechanical s ...
properties were discovered by
Jacques Ancient and noble French family names, Jacques, Jacq, or James are believed to originate from the Middle Ages in the historic northwest Brittany region in France, and have since spread around the world over the centuries. To date, there are over ...
and
Pierre Curie Pierre Curie ( , ; 15 May 1859 – 19 April 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity, and radioactivity. In 1903, he received the Nobel Prize in Physics with his wife, Marie Curie, and Henri Becqu ...
in 1880. The
quartz oscillator A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable cloc ...
or resonator was first developed by
Walter Guyton Cady Walter Guyton Cady (December 10, 1874 – December 9, 1974) was a noted American physicist and electrical engineer. He was a pioneer in piezoelectricity, and in 1921 developed the first quartz crystal oscillator. Cady was born in Providence, Rho ...
in 1921.
George Washington Pierce George Washington Pierce (January 11, 1872 – August 25, 1956) was an American physicist. He was a professor of physics at Harvard University and inventor in the development of electronic telecommunications. The son of a Texas cattle rancher, h ...
designed and patented quartz crystal oscillators in 1923. Warren Marrison created the first quartz oscillator clock based on the work of Cady and Pierce in 1927. Efforts to synthesize quartz began in the mid-nineteenth century as scientists attempted to create minerals under laboratory conditions that mimicked the conditions in which the minerals formed in nature: German geologist Karl Emil von Schafhäutl (1803–1890) was the first person to synthesize quartz when in 1845 he created microscopic quartz crystals in a
pressure cooker Pressure cooking is the process of cooking food under high pressure steam and water or a water-based cooking liquid, in a sealed vessel known as a ''pressure cooker''. High pressure limits boiling, and creates higher cooking temperatures which c ...
. However, the quality and size of the crystals that were produced by these early efforts were poor. By the 1930s, the electronics industry had become dependent on quartz crystals. The only source of suitable crystals was Brazil; however,
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
disrupted the supplies from Brazil, so nations attempted to synthesize quartz on a commercial scale. German mineralogist Richard Nacken (1884–1971) achieved some success during the 1930s and 1940s. After the war, many laboratories attempted to grow large quartz crystals. In the United States, the U.S. Army Signal Corps contracted with
Bell Laboratories Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984), then AT&T Bell Laboratories (1984–1996) and Bell Labs Innovations (1996–2007), is an American industrial research and scientific development company owned by mult ...
and with the
Brush Development Company Brush Development Company was a manufacturer of Audio equipment, audio, phonographic products and magnetic recording technologies located in Cleveland, Ohio. It was absorbed into Clevite in 1952. History The business was founded in 1919 by Alfred ...
of Cleveland, Ohio to synthesize crystals following Nacken's lead. (Prior to World War II, Brush Development produced piezoelectric crystals for record players.) By 1948, Brush Development had grown crystals that were 1.5 inches (3.8 cm) in diameter, the largest to date. By the 1950s, hydrothermal synthesis techniques were producing synthetic quartz crystals on an industrial scale, and today virtually all the quartz crystal used in the modern electronics industry is synthetic. File:Milan Jug with cut festoon decoration.jpg, Rock crystal jug with cut festoon decoration by
Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
workshop from the second half of the 16th century,
National Museum A national museum is a museum maintained and funded by a national government. In many countries it denotes a museum run by the central government, while other museums are run by regional or local governments. In other countries a much greater numb ...
in
Warsaw Warsaw ( pl, Warszawa, ), officially the Capital City of Warsaw,, abbreviation: ''m.st. Warszawa'' is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland, and its population is officia ...
. The city of Milan, apart from
Prague Prague ( ; cs, Praha ; german: Prag, ; la, Praga) is the capital and largest city in the Czech Republic, and the historical capital of Bohemia. On the Vltava river, Prague is home to about 1.3 million people. The city has a temperate ...
and
Florence Florence ( ; it, Firenze ) is a city in Central Italy and the capital city of the Tuscany region. It is the most populated city in Tuscany, with 383,083 inhabitants in 2016, and over 1,520,000 in its metropolitan area.Bilancio demografico an ...
, was the main
Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ideas ...
centre for crystal cutting. File:Prototype synthetic quartz autoclave 1959.jpg, Synthetic quartz crystals produced in the autoclave shown in
Western Electric The Western Electric Company was an American electrical engineering and manufacturing company officially founded in 1869. A wholly owned subsidiary of American Telephone & Telegraph for most of its lifespan, it served as the primary equipment ma ...
's pilot hydrothermal quartz plant in 1959 File:Ewer birds Louvre MR333.jpg,
Fatimid The Fatimid Caliphate was an Ismaili Shi'a caliphate extant from the tenth to the twelfth centuries AD. Spanning a large area of North Africa, it ranged from the Atlantic Ocean in the west to the Red Sea in the east. The Fatimids, a dy ...
ewer in carved rock crystal (clear quartz) with gold lid, c. 1000.


Piezoelectricity

Quartz crystals have
piezoelectric Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied Stress (mechanics), mechanical s ...
properties; they develop an
electric potential The electric potential (also called the ''electric field potential'', potential drop, the electrostatic potential) is defined as the amount of work energy needed to move a unit of electric charge from a reference point to the specific point in ...
upon the application of
mechanical stress In continuum mechanics, stress is a physical quantity. It is a quantity that describes the magnitude of forces that cause deformation. Stress is defined as ''force per unit area''. When an object is pulled apart by a force it will cause elonga ...
. An early use of this property of quartz crystals was in
phonograph A phonograph, in its later forms also called a gramophone (as a trademark since 1887, as a generic name in the UK since 1910) or since the 1940s called a record player, or more recently a turntable, is a device for the mechanical and analogu ...
pickups. One of the most common piezoelectric uses of quartz today is as a
crystal oscillator A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable cloc ...
. The
quartz clock Quartz clocks and quartz watches are timepieces that use an electronic oscillator regulated by a quartz crystal to keep time. This crystal oscillator creates a signal with very precise frequency, so that quartz clocks and watches are at least an ...
is a familiar device using the mineral. The resonant frequency of a quartz crystal oscillator is changed by mechanically loading it, and this principle is used for very accurate measurements of very small mass changes in the
quartz crystal microbalance A quartz crystal microbalance (QCM) (also known as ''quartz microbalance'' (QMB), sometimes also as ''quartz crystal nanobalance'' (QCN)) measures a mass variation per unit area by measuring the change in frequency of a quartz crystal resonator. The ...
and in
thin-film thickness monitor Thin-film thickness monitors, deposition rate controllers, and so on, are a family of instruments used in high and ultra-high vacuum systems. They can measure the thickness of a thin film, not only after it has been made, but while it is still bei ...
s. (NB. This was partially presented at Physikertagung in Heidelberg in October 1957.)


See also

*
Fused quartz Fused quartz, fused silica or quartz glass is a glass consisting of almost pure silica (silicon dioxide, SiO2) in amorphous (non-crystalline) form. This differs from all other commercial glasses in which other ingredients are added which change ...
*
List of minerals This is a list of minerals for which there are articles on Wikipedia. Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various ''species''. Within a m ...
* Quartz fiber *
Quartz reef mining Quartz reef mining is a type of gold mining in "reefs" (veins) of quartz. Quartz is one of the most common minerals in the earth's crust, and most quartz veins do not carry gold, but those that have gold are avidly hunted by prospectors. In the sh ...
* Quartzolite *
Shocked quartz Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. Under intense pressure (but limited temperature), the crystalline structure of quartz is deformed along planes inside the crystal. These pla ...


References


External links


Quartz varieties, properties, crystal morphology. Photos and illustrations


* * ttps://web.archive.org/web/20071012101816/http://www.connogue.com/quartslab/html/terminology.html Terminology used to describe the characteristics of quartz crystals when used as oscillators
Quartz use as prehistoric stone tool raw material
{{Authority control Dielectrics Piezoelectric materials Symbols of Georgia (U.S. state) Trigonal minerals Minerals in space group 152 or 154 Minerals in space group 180 or 181 Luminescent minerals Quartz gemstones Industrial minerals Silica polymorphs Symbols of South Dakota