Amethyst Chemical composition: SiO2 (minor Fe4+ impurities cause amethyst's color)
Class: tectosilicateCrystal system: Hexagonal-R; 32 (trigonal-trapezohedral)Crystal habit: Macroscopic crystals occur as horizontally striated hexagonal prisms terminated by a combination of positive and negative rhombohedrons forming six sided pyramids. Amethyst often occurs as drusy masses showing only the rhobohedral terminations. It can also be massive.Twinning: Dauphine twin with c the twin axis, Brazil twin with {1120} the twin planeSpecific gravity: 2.65Index of refraction: 1.54-1.55Birefringence: 0.009Pleochroism: distinctHardness: 7Color: light to dark purpleLuster: vitreousTransparency: transparent to translucentCleavage: noneFracture: conchoidalStreak: white
!
SwissGemShop
Your source of loose Precious & Semi Precious Gemstones Gem quality Gemstones at sale price A lot of information to learn about Gemstones