Imperial topaz
Variety Al2SiO4(F,OH)2
Also called Precious topaz
About it
Golden orange to pinkish orange topaz, the most prized colour. Comes mostly from around Ouro Preto in Minas Gerais, Brazil; its perfect cleavage means cut stones should be guarded from knocks.
- Type
- Variety
- Group
- Topaz variety
- Formula
- Al2SiO4(F,OH)2
- Hardness (Mohs)
- 8
- Specific gravity
- 3.5–3.57
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Orthorhombic
- Colours
- golden orange, pinkish orange, sherry, red
- Transparency
- transparent
- Cleavage and fracture
- perfect basal in one direction; conchoidal fracture
Typical values: real specimens vary. For more, see mindat.org.