Amazonite
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Amazonite, also known as Amazonstone, is a green
tectosilicate Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust. In mineralogy, silica (silicon dioxide, ) is usually consid ...
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. ( ...
, a variety of the potassium feldspar called
microcline Microcline (KAlSi3O8) is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slow ...
. Its
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, ...
is KAlSi3O8, which is polymorphic to
orthoclase Orthoclase, or orthoclase feldspar (endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles t ...
. Its name is taken from that of the
Amazon River The Amazon River (, ; es, Río Amazonas, pt, Rio Amazonas) in South America is the largest river by discharge volume of water in the world, and the disputed longest river system in the world in comparison to the Nile. The headwaters of t ...
, from which green stones were formerly obtained, though it is unknown whether those stones were amazonite. Although it has been used for over two thousand years, as attested by archaeological finds in Egypt and Mesopotamia, no ancient or medieval authority mentions it. It was first described as a distinct mineral only in the 18th century.Mikhail Ostrooumov, ''Amazonite: Mineralogy, Crystal Chemistry, and Typomorphism'' (Elsevier, 2016), p. 1-12. Green and greenish-blue varieties of potassium feldspars that are predominantly triclinic are designated as amazonite. It has been described as a "beautiful crystallized variety of a bright verdigris-green" and as possessing a "lively green colour." It is occasionally cut and used as a
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, ...
.


Occurrence

Amazonite is a mineral of limited occurrence. Formerly it was obtained almost exclusively from the area of
Miass Miass ( rus, Миа́сс, p=mʲɪˈas) is a city in Chelyabinsk Oblast, Russia, located west of Chelyabinsk, on the eastern slope of the Southern Ural Mountains, on the bank of the river Miass. Population: Name The name Miass is taken from ...
in the
Ilmensky Mountains The Ilmensky Mountains (russian: links=no, Ильменские горы, translit=Il'menskiye gory) are located in the Southern Urals in the Chelyabinsk Oblast on the administrative territory of Miass in Chebarkulsky and Argayashsky districts. ...
, 50 miles southwest of
Chelyabinsk Chelyabinsk ( rus, Челя́бинск, p=tɕɪˈlʲæbʲɪnsk, a=Ru-Chelyabinsk.ogg; ba, Силәбе, ''Siläbe'') is the administrative center and largest city of Chelyabinsk Oblast, Russia. It is the seventh-largest city in Russia, with a ...
,
Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...
, where it occurs in
granitic rocks A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quart ...
. Amazonite is now known to occur in various places around the globe. Those places are, among others, as follows: China: * Baishitouquan granite intrusion,
Hami Prefecture Hami (Kumul) is a prefecture-level city in Eastern Xinjiang, China. It is well known as the home of sweet Hami melons. In early 2016, the former Hami county-level city was merged with Hami Prefecture to form the Hami prefecture-level city with t ...
,
Xinjiang Xinjiang, SASM/GNC: ''Xinjang''; zh, c=, p=Xīnjiāng; formerly romanized as Sinkiang (, ), officially the Xinjiang Uygur Autonomous Region (XUAR), is an autonomous region of the People's Republic of China (PRC), located in the northwest ...
: found in granite Libya: * Jabal Eghei,
Tibesti Mountains The Tibesti Mountains are a mountain range in the central Sahara, primarily located in the extreme north of Chad, with a small portion located in southern Libya. The highest peak in the range, Emi Koussi, lies to the south at a height of and i ...
: found in granitic rocks Mongolia: * Avdar Massif,
Töv Province Töv ( mn, Төв, , ; "central") is one of the 21 Aimags of Mongolia, aimags (provinces) of Mongolia. The national capital Ulaanbaatar is located roughly at its center, but the city itself is administrated as an independent municipality. Geogr ...
: found in alkali granite South Africa: * Mogalakwena, Limpopo Province * Khâi-Ma, Northern Cape *
Kakamas Kakamas is a town founded in 1898 and located in the Northern Cape province of South Africa, on the banks of the Orange River. Originated as at a place where the Orange River could be relatively easily crossed. The spot was first known as Basso ...
, Northern Cape * Ceres Valley, Western Cape Sweden: * Skuleboda mine,
Västra Götaland County Västra Götaland County ( sv, Västra Götalands län) is a county or '' län'' on the western coast of Sweden. The county is the second most populous of Sweden's counties and it comprises 49 municipalities (''kommuner''). Its population of 1 ...
: found in pegmatite United States: * Colorado: **
Deer Trail The Town of Deer Trail is a Statutory Town located in eastern Arapahoe County, Colorado, United States. The town population was 1,068 at the 2020 United States Census, a +95.60% increase since the 2010 United States Census. Deer Trail is a part ...
, Arapahoe County:233 ** Custer County:234 ** Devils Head, Douglas County:234 ** Pine Creek, Douglas County:234 ** Crystal Park, El Paso County:234 **
Pikes Peak Pikes Peak is the List of mountain ranges of Colorado#Mountain ranges, highest summit of the southern Front Range of the Rocky Mountains, in North America. The Ultra-prominent peak, ultra-prominent fourteener is located in Pike National Forest ...
, El Paso County: found in coarse granites or
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 ...
** St. Peter's Dome, El Paso County:234 **
Tarryall Mountains Tarryall is an unincorporated town of cabins and old buildings in eastern Park County, Colorado, United States. The town is located on Tarryall Creek Tarryall Creek is a tributary of the South Platte River, approximately long,U.S. Geological ...
, Park County:235 ** Crystal Peak, Teller County:235 * Virginia: ** Morefield Mine, Amelia County: found in pegmatite ** Rutherford Mine, Amelia County * Pennsylvania: **
Media Media may refer to: Communication * Media (communication), tools used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Broadcast media, communications delivered over mass el ...
, Delaware County:244 ** Middletown, Delaware County:244


Color

For many years, the source of amazonite's color was a mystery. Some people assumed the color was due to copper because
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
compounds often have blue and green colors. A 1985 study suggests that the blue-green color results from quantities of
lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...
and water in the feldspar. Subsequent 1998 theoretical studies by A. Julg expand on the potential role of aliovalent lead in the color of microcline. Other studies suggest the colors are associated with the increasing content of lead,
rubidium Rubidium is the chemical element with the symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have a density higher ...
, and
thallium Thallium is a chemical element with the Symbol (chemistry), symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists W ...
ranging in amounts between 0.00X and 0.0X in the feldspars, with even extremely high contents of PbO,
lead monoxide Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula Pb O. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern ap ...
, (1% or more) known from the literature. A 2010 study also implicated the role of divalent
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 ...
in the green coloration. These studies and associated hypotheses indicate the complex nature of the color in amazonite; in other words, the color may be the aggregate effect of several mutually inclusive and necessary factors.


Health

A 2021 study by the German Institut für Edelsteinprüfung (EPI) found that the amount of lead that leaked from an sample of Amazonite into an acidic solution simulating saliva exceeded
European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
standard DIN EN 71-3:2013's recommended amount by five times. This experiment was to simulate a child swallowing Amazonite, and could also apply to new wellness practices such as inserting the mineral into oils or drinking water for days.


Gallery

File:Microcline-Quartz-Albite-48224.jpg, Deep robins-egg blue color amazonite crystal on
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 ...
and
albite Albite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. It represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula . It is a tectosilicate. I ...
, from
Teller County, Colorado Teller County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 24,710. The county seat is Cripple Creek, and the most populous city is Woodland Park. Teller County is included in the Colorado Sprin ...
(size: 3.4 x 3.3 x 2.5 cm). File:Amazonite, quartz 300-3-7927.JPG, Amazonite crystal on
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 ...
, from
Pikes Peak Pikes Peak is the List of mountain ranges of Colorado#Mountain ranges, highest summit of the southern Front Range of the Rocky Mountains, in North America. The Ultra-prominent peak, ultra-prominent fourteener is located in Pike National Forest ...
,
El Paso County, Colorado El Paso County is a county located in the U.S. state of Colorado. The 2020 Census recorded its population as 730,395. The Census Bureau's 2020 result indicates it is the most populous county in Colorado, surpassing the City and County of De ...
File:Microcline-179612.jpg, Large deep-turquoise amazonite crystal with attached stark-white microcline, from Konso,
SNNPR The Southern Nations, Nationalities, and Peoples' Region (often abbreviated as SNNPR; am, የደቡብ ብሔር ብሔረሰቦችና ሕዝቦች ክልል, Yädäbub Bḥer Bḥeräsäbočna Hzboč Kllə) is a regional state in southwestern E ...
, Ethiopia (size: 16.4 x 11.9 x 8.0 cm). File:Microcline-Quartz-206935.jpg, Two
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 ...
crystals surrounded by amazonite crystals, from Smoky Hawk Mine, Crystal Peak,
Teller County, Colorado Teller County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 24,710. The county seat is Cripple Creek, and the most populous city is Woodland Park. Teller County is included in the Colorado Sprin ...
(11.0 x 8.2 x 6.3 cm). File:Amazonite 1.jpg, Amazonite crystals on
orthoclase Orthoclase, or orthoclase feldspar (endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles t ...
, from Konso,
SNNPR The Southern Nations, Nationalities, and Peoples' Region (often abbreviated as SNNPR; am, የደቡብ ብሔር ብሔረሰቦችና ሕዝቦች ክልል, Yädäbub Bḥer Bḥeräsäbočna Hzboč Kllə) is a regional state in southwestern E ...
, Ethiopia. File:Microcline-20436.jpg, Deep lustrous crystal of amazonite, from Take 5 Claim, Crystal Peak,
Teller County, Colorado Teller County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 24,710. The county seat is Cripple Creek, and the most populous city is Woodland Park. Teller County is included in the Colorado Sprin ...
(size: 4.4 x 4 x 3.5 cm). File:Landsverk-1 amazonite+ordførerkjede.jpg, Amazonite from the Landsverk 1 mine with the
livery collar A livery collar or chain of office is a collar or heavy chain, usually of gold, worn as insignia of office or a mark of fealty or other association in Europe from the Middle Ages onwards. One of the oldest and best-known livery collars is the Col ...
of the mayor of
Evje Evje is a former municipality in the old Aust-Agder county in Norway. The municipality existed from 1877 until 1960. It was located in what is now the eastern part of the present-day municipality of Evje og Hornnes in the Setesdal valley of Ag ...
,
Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...
. (size: 21x22 cm). File:LANDSVERK-1 mikroklien-verdringt-amazoniet.jpg, Amazonite partly altered to brown microcline from the Landsverk 1 mine in Evje, Norway. File:Amazonite specimen (polished) arp.jpg, Polished Amazonite specimen. Height 13 cm (5 in).


References


Further reading

*


External links

{{Gemstones Feldspar Gemstones