Calcite (sparry) (Iceland Spar)CaCO3|
Habit: Large crystals, some exhibiting common twin striae
| ||Crystal System: Hexagonal|
Cleavage: Perfect rhombohedral
Reaction with HCl: Strong
Identification in hand sample:
Hardness, crystal habit and twin striae are typical.
Common as a cementing agent in clastic sediments or as fossil fragments.
Industrial / ecomonic uses:
Used in the manufacture of portland cement (quicklime) and in the pharmaceutical industry.
The transparent variety is called "Iceland Spar".