Amazonite

Amazonite occurs in pegmatites, granites and related rocks; well-formed crystals usually grow in pegmatites and cavities. Despite its name, there are no known sources within the Amazon rainforest or near the Amazon River. Brazil (Minas Gerais, Paraíba and Rio Grande do Norte) and Peru (Huancavelica) produce fine material; in the United States the Pikes Peak area of Colorado, where it is often found with smoky quartz, and Amelia Court House, Virginia, are known sources. Ethiopia has become a producer of top-quality amazonite. Other sources include Canada, China, Madagascar, Mozambique, Myanmar, Pakistan and Russia.

Amazonite is recognized by its green to bluish-green color, often interrupted by white streaks or a cross-hatched pattern, two directions of perfect cleavage meeting near 90°, and a pearly luster on some cleavage faces. Its refractive index (1.522–1.530) and specific gravity (about 2.54–2.63) are those of microcline. Mineralogists caution that the name is sometimes over-applied to slightly gray-green microcline.

Treatments include dyeing, wax impregnation, plastic coating and irradiation; the color is lost when the stone is heated above about 300 °C. "Amazon jade" is a misleading trade name: amazonite is a feldspar, not jadeite or nephrite.

With a Mohs hardness of 6 to 6.5 and perfect cleavage, amazonite can be scratched in everyday wear and may break if struck. It is best suited to earrings, pendants and brooches; rings and bracelets benefit from protective (for example bezel) settings. Avoid steam and ultrasonic cleaning, which can widen internal fractures and remove coatings or fillers from treated stones. Clean with a soft brush, mild detergent and warm water.

Amazonite has been used since about 3000 BCE for decorations, amulets, vessels and beads; ancient examples have been found in Egypt, Mesopotamia and northern India, and it was counted among the six most precious stones in Pharaonic Egypt. A Babylonian cylinder seal carved from amazonite dates to the 15th century BCE. The stone has been linked by name with the Amazon since at least 1701, first as "Amazon stone". The mineralogist August Breithaupt formally named it amazonite in 1847, after an unspecified locality "near" the Amazon River.