Amazonite

Amazonite is the green to blue-green gem variety of microcline, a potassium feldspar with the composition KAlSi3O8. Its distinctive color is attributed to trace amounts of lead and structural water rather than to copper. The mineral crystallizes in the triclinic system with a Mohs hardness of 6 to 6.5 and a specific gravity near 2.57, showing a vitreous luster, a white streak, and perfect {001} cleavage. Crystals are typically prismatic or tabular, though massive material is common. Despite the name, amazonite has never been found in the Amazon River basin; the label most likely derives from green stones traded from an unrelated source. It is cut as a cabochon and used ornamentally for the soft turquoise hue that sets it apart from ordinary feldspar.

Amazonite is a green to blue-green variety of microcline feldspar. Its color is attributed to trace amounts of lead and water in the crystal structure. Despite its name, it has never been found in the Amazon River basin; it was likely named for green stones from another source.