Amethyst

Quartz (var. Amethyst) Aggregate of pale lavender to violet, translucent quartz crystals (var. amethyst) forming a dense crystalline to drusy coating on a light-coloured quartz-rich substrate or matrix. Individual crystals are predominantly subhedral to euhedral and short prismatic to stubby, with well-developed terminal rhombohedral faces. Crystal size and orientation are variable, producing an irregular intergrown aggregate with locally developed clusters of larger crystals. Crystal surfaces exhibit vitreous lustre. Amethyst colouration is unevenly distributed, ranging from very pale lavender to moderate violet, with locally colourless to pale yellow-brown areas. Minor broken or incomplete crystals occur along the specimen margins. In general, Amethyst (SiO2) is the purple variety of Quartz. Lustre is vitreous or greasy and streak is white. Hardness is 7. Quartz usually occurs as prismatic crystals that are terminated by double rhombohedrons with striations crosswise. Quartz can also be disseminated, granular or massive.