The Crystal Cave

Amethyst

SiO₂

Silicate, (tectosilicate, silica group) a silicon oxide.
Appearance: The color is violet, are caused by trace of iron oxide. Occurs in wellformed crystals or compact and concretionary masses, even massif.
Hardness: 7
SG: 2,6
Transparant to translucent with vitreous luster.
Crystal system: Trigonal, Hexagonal.
Environment: Are often found in geodes of vulcanic rocks.