Inclusions of native copper and tenorite (CuO) were found in grayish green elbaite from São José da Batalha, Paraíba, Brazil. Native copper forms strongly dendritic platelets (about 100 µ long, 1 µ ...

Amethyst may develop into the more common citrine and rarer green quartz naturally under certain geologic conditions. On the California-Nevada border, just north of Reno, amethyst, citrine, and green ...

Two Antique Mughal Spectacles with Gemstone Lenses Unique diamond and emerald-lensed spectacles from the Mughal Empire were tested in GIA’s New York laboratory. Read More ...