Amazonite, also known as Amazonstone, is a green tectosilicate mineral, a variety of the potassium feldspar called microcline.
Its chemical formula is KAlSi3O8, which is polymorphic to orthoclase.
Its name is taken from that of the Amazon River, 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.
Occurrence
Amazonite is a mineral of limited occurrence.
Formerly it was obtained almost exclusively from the area of Miass in the Ilmensky Mountains, 50 miles southwest of Chelyabinsk, Russia, where it occurs in granitic rocks.
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, Xinjiang: found in granite
Libya:
Jabal Eghei, Tibesti Mountains: found in granitic rocks
Mongolia:
Avdar Massif, Töv Province: found in alkali granite
South Africa:
Mogalakwena, Limpopo Province
Khâi-Ma, Northern Cape
Kakamas, Northern Cape
Ceres Valley, Western Cape
United States:
Colorado:
Deer Trail, Arapahoe County:233
Custer County:234
Devils Head, Douglas County:234
Pine Creek, Douglas County:234
Crystal Park, El Paso County:234
Pikes Peak, El Paso County: found in coarse granites or pegmatite
St. Peter's Dome, El Paso County:234
Tarryall Mountains, Park County:235
Crystal Peak, Teller County:235
Virginia:
Morefield Mine, Amelia County: found in pegmatite
Rutherford Mine, Amelia County
Pennsylvania:
Media, 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 compounds often have blue and green colors.
A 1985 study suggest that the blue-green color results from quantities of lead 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, and thallium ranging in amounts between 0.00X and 0.0X in the feldspars, with even extremely high contents of PbO, lead monoxide, (1% or more) known from the literature.
A recent 2010 study also implicated the role of divalent iron in the green coloration.
These studies and associated hypotheses indicate the complex nature of the color in amazonite, in other words 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 a  sample of Amazonite into an acidic solution simulating saliva exceeded European Union 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 and albite, from Teller County, Colorado (size: 3.4 x 3.3 x 2.5 cm).
File:Amazonite, quartz 300-3-7927.JPG|Amazonite crystal on smoky quartz, from Pikes Peak, El Paso County, Colorado File:Microcline-179612.jpg|Large deep-turquoise amazonite crystal with attached stark-white microcline, from Konso, SNNPR, Ethiopia (size: 16.4 x 11.9 x 8.0 cm).
File:Microcline-Quartz-206935.jpg|Two smoky quartz crystals surrounded by amazonite crystals, from Smoky Hawk Mine, Crystal Peak, Teller County, Colorado (11.0 x 8.2 x 6.3 cm).
File:Amazonite 1.jpg|Amazonite crystals on orthoclase, from Konso, SNNPR, Ethiopia.
File:Microcline-20436.jpg|Deep lustrous crystal of amazonite, from Take 5 Claim, Crystal Peak, Teller County, Colorado (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 of the mayor of Evje, Norway.
(size: 21x22 cm).
File:LANDSVERK-1 mikroklien-verdringt-amazoniet.jpg|thumb|Amazonite partly altered to brown microcline from the Landsverk 1 mine in Evje, Norway.
File:Amazonite specimen (polished) arp.jpg|thumb|Polished Amazonite specimen.
Height 13 cm (5 in).
References
Further reading
External links
