Amethyst

This large geode structure of amethyst is on display in the Smithsonian Museum of Natural History. Amethyst is a variety of quartz with the characteristic composition SiO₂, but distinctive and popular for its dramatic purple color.

This geode is about 40x35 cm and is from Rio Grande do Sul, Brazil. It is described as amethyst formed with calcite.

This interesting formation of quartz crystals is about 14x25 cm and is from Minas Gerais, Brazil. It is not identified as amethyst, but it appears to be that variety.

This is a closer view of one of the crystal clusters of the sample above.

The large single crystal of amethyst above left is about 4x4 cm and is from North Carolina. The gem above left is 1362 carats and is from Jacobea mine, Bahia, Brazil. The sample above right is about 17x15 cm and is from Diamond Willow mine, Pearl, Ontario,Canada.

This sample is about 10x7 cm and is from Vera Cruz, Mexico.

This huge display of amethyst crystals is about 60x60 cm and is from Guerrero, Mexico.

This sample of amethyst is about 7x7 cm.