Amethyst
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameAmethyst
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorspurple, white, grey
Transparencytransparent
Type LocalityJuchem Quarry, Niederwörresbach, Idar-Oberstein, Hunsrück Mts, Germany
Mineral GroupSilicates
Usesjewelry, collector, decorative
Associated Mineralsagate, chalcedony, calcite
Raritycommon
Description
This specimen is an amethyst geode, showcasing a cavity lined with numerous vibrant purple quartz crystals. The outer matrix of the geode is a rough, greyish-white rock.
Geological Context
Amethyst typically forms in geodes or veins within volcanic rocks, such as basalt, where silica-rich fluids deposit quartz crystals. The distinctive purple color is attributed to irradiation and trace amounts of iron impurities within the crystal lattice.
