Ametrine Chemical composition: SiO2 (minor iron impurities cause ametrine's colors)
Class: tectosilicate
Crystal 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. It can also be massive.
Twinning: Dauphine twin with c the twin axis, Brazil twin with {1120} the twin plane
Specific gravity: 2.65
Index of refraction: 1.54-1.55
Birefringence: 0.009
Pleochroism: distinct
Hardness: 7
Color: two distinct colors present, yellow-orange and purple
Luster: vitreous
Transparency: transparent to translucent
Cleavage: none
Fracture: conchoidal
Streak: white