Iceland spar
Variety CaCO3
Also called Optical calcite
About it
Water-clear calcite that splits into rhombs and shows a strong double image of anything viewed through it. Named for the classic mine at Helgustaðir in eastern Iceland; also from Mexico and China.
- Type
- Variety
- Group
- Calcite variety
- Formula
- CaCO3
- Hardness (Mohs)
- 3
- Specific gravity
- 2.71
- Streak
- white
- Lustre
- vitreous (glassy)
- Crystal system
- Trigonal
- Colours
- colourless
- Transparency
- transparent
- Cleavage and fracture
- perfect rhombohedral in three directions
Typical values: real specimens vary. For more, see mindat.org.