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Amazonite from Brazil
Category Tectosilicate
(repeating unit)
Crystal system Triclinic
ColorGreen, blue-green
Crystal habit Prismatic
Cleavage Perfect
Fracture Uneven, splintery
Tenacity Brittle
Mohs scale hardness6.0–6.5
Luster Vitreous
Streak White
Diaphaneity Translucent, opaque
Specific gravity 2.56–2.58
Refractive index 1.522–1.530
Birefringence −0.008
Pleochroism Absent
Dispersion None
Ultraviolet fluorescence Weak; olive-green
Other characteristics Radioactive.svg Radioactive 14.05% (K)
References [1] [2] [3] :214-215

Amazonite, also known as Amazonstone, [4] is a green tectosilicate mineral, a variety of the potassium feldspar called microcline. [4] [5] Its chemical formula is KAlSi3O8, [1] [6] 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. [4] Although it has been used for jewellery for well over three thousand years, as attested by archaeological finds in Middle and New Kingdom Egypt [7] and Mesopotamia, no ancient or medieval authority mentions it. It was first described as a distinct mineral only in the 18th century. [8]

Green and greenish-blue varieties of potassium feldspars that are predominantly triclinic are designated as amazonite. [9] It has been described as a "beautiful crystallized variety of a bright verdigris-green" [10] and as possessing a "lively green colour." [4] It is occasionally cut and used as a gemstone. [11]


Amazonite is a mineral of limited occurrence. In Bronze Age Egypt, it was mined in the southern Eastern Desert at Gebel Migif. In early modern times, it was obtained almost exclusively from the area of Miass in the Ilmensky Mountains, 50 miles (80 km) southwest of Chelyabinsk, Russia, where it occurs in granitic rocks. [4]

Amazonite is now known to occur in various places around the globe. Those places are, among others, as follows:




South Africa:


United States:


For many years, the source of amazonite's color was a mystery. [18] Some people assumed the color was due to copper because copper compounds often have blue and green colors. [18] A 1985 study suggests that the blue-green color results from quantities of lead and water in the feldspar. [18] Subsequent 1998 theoretical studies by A. Julg expand on the potential role of aliovalent lead in the color of microcline. [19]

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. [9] A 2010 study also implicated the role of divalent iron in the green coloration. [6] 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. [8]


A 2021 study by the German Institut für Edelsteinprüfung (EPI) found that the amount of lead that leaked from an 11 g (0.39 oz) 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. [20]

Related Research Articles

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Orthoclase, or orthoclase feldspar (endmember formula KAlSi3O8), 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 to each other. It is a type of potassium feldspar, also known as K-feldspar. The gem known as moonstone (see below) is largely composed of orthoclase.

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Further reading

Commons-logo.svg Media related to Amazonite at Wikimedia Commons