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, macros ...
mineral composed of silica (
silicon dioxide). The atoms are linked in a continuous framework of SiO
4 silicon-oxygen
tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall
chemical formula of
SiO2. Quartz is the second most abundant
mineral 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.
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 i ...
. 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
gemstones. Since antiquity, varieties of quartz have been the most commonly used minerals in the making of
jewelry and
hardstone carvings, especially in
Eurasia.
Quartz is the
mineral 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 word "Quarz", which had the same form in the first half of the 14th century in
Middle High German 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 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 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 p ...
''κρύος'' (''kruos'') meaning "icy cold", because some
philosophers (including
Theophrastus) 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 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
pyramids at each end. In
nature 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
geodes 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.
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 uncha ...
''P''3
121 or ''P''3
221 (space group 152 or 154 resp.) depending on the chirality. Above , α-quartz in ''P''3
121 becomes the more symmetric hexagonal ''P''6
422 (space group 181), and α-quartz in ''P''3
221 goes to space group ''P''6
222 (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 (SiO
4 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 carvings, such as the
Lothair Crystal. 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 or
cryptocrystalline 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 monocli ...
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 ...
consisting of fine intergrowths of both quartz, and its
monoclinic 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 Anci ...
,
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 used ...
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 ...
,
heliotrope, and
jasper.
Amethyst
Amethyst 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. Amethyst derives its color from traces of iron in its structure.
Blue quartz
Blue quartz contains inclusions of fibrous
magnesio-riebeckite or
crocidolite.
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 hue. Shades of
purple or
grey 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 sp ...
hydroxide impurities. Natural citrines are rare; most commercial citrines are heat-treated amethysts 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 visually, but they differ in hardness. Brazil is the leading producer of citrine, with much of its production coming from the state of Rio Grande do Sul. 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. 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, iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
, or manganese, 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 polymorphs of TiO2 are known, including anatase, akaogiite, and brookite.
Rutile has one of the highest refractive indices at visib ...
needles that produce asterism in transmitted light. Recent X-ray diffraction 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 or aluminium. The color in crystals is apparently photosensitive and subject to fading. The first crystals were found in a pegmatite 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 ...
, US and in Minas Gerais, 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, 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. Naturally occurring prasiolite is also found in the Thunder Bay 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, 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 used ...
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 sterilizati ...
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 and other felsic igneous rock
Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...
s. It is very common in sedimentary rocks such as sandstone and shale. It is a common constituent of schist, gneiss, quartzite and other metamorphic rocks. Quartz has the lowest potential for weathering 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
Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty.
Common types of dirt include:
* Debri ...
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, 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 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 ...
, 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 pegmatites. 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 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 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 territori ...
. Quartz may also be found in Caldoveiro Peak, 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 community in northwest Spain.
It is coextensiv ...
, 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 kilograms.
Mining
Quartz is extracted from open pit mines. Miners occasionally use explosives to expose deep pockets of quartz. More frequently, bulldozers and backhoes 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 has increased the demand for natural quartz crystals, which are now often mined in developing countries 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 describe ...
and cristobalite are high-temperature polymorphs of SiO2 that occur in high-silica volcanic 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 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 ...
SiO2 which is formed by lightning strikes in quartz sand.
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 and may lead to other diseases of the lungs such as silicosis 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 , which is of Slavic origin (Czech miners called it ''křemen''). Other sources attribute the word's origin to the Saxon 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 language groups across Australia in their ceremonies. Aboriginal spirituality includes ...
. It is found regularly in passage tomb cemeteries in Europe in a burial context, such as Newgrange 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 tools; 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 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 Geography, geographical and culture, ethno-cultural terms. The modern State (polity), states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. ...
and Pre-Columbian America, in Europe and the Middle East the different varieties of quartz were the most commonly used for the various types of jewelry and hardstone carving, 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 lux ...
s and cameo gems, rock crystal vases, 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 opaqu ...
, 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.
In the 17th century, Nicolas Steno's study of quartz paved the way for modern crystallography. 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 mechanical stress. The word '' ...
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 in 1880. The quartz oscillator 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 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. 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 opposing ...
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 and with the Brush Development Company 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 in Warsaw. The city of Milan, apart from Prague
Prague ( ; cs, Praha ; german: Prag, ; la, Praga) is the capital and List of cities in the Czech Republic, largest city in the Czech Republic, and the historical capital of Bohemia. On the Vltava river, Prague is home to about 1.3 milli ...
and Florence, was the main Renaissance
The Renaissance ( , ) , from , with the same meanings. is a period in European history
The history of Europe is traditionally divided into four time periods: prehistoric Europe (prior to about 800 BC), classical antiquity (800 BC to AD ...
centre for crystal cutting.
File:Prototype synthetic quartz autoclave 1959.jpg, Synthetic quartz crystals produced in the autoclave shown in Western Electric'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 dyna ...
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 mechanical stress. The word '' ...
properties; they develop an electric potential 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 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 clock ...
. The quartz clock 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 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
* 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
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
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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