Amethyst
Image: <a href="//commons.wikimedia.org/wiki/User:Archaeodontosaurus" title="User:Archaeodontosaurus">Didier Descouens</a> (CC BY-SA 3.0)
Mineral NameAmethyst
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorspurple, violet
Transparencytranslucent
Type LocalityMun. Las Vigas de Ramírez (Mun. de Profesor Rafael Ramírez), Veracruz, Mexico
Mineral GroupSilicates
Usesjewelry, collector, ornamental
Associated Mineralscalcite, zeolites, goethite, hematite
Raritycommon
Description
This specimen features numerous purple amethyst crystals, mostly short and stubby, embedded within a light-colored, rough matrix rock. The crystals vary in intensity of purple color and are scattered across the surface of the host rock.
Geological Context
Amethyst forms in hydrothermal veins and cavities within igneous rocks, particularly basaltic lavas, where silica-rich fluids deposit quartz. The purple color is due to irradiation of iron impurities within the quartz lattice.
