Description:
Calcite (KAL-site) is a mineral species; hexagonal (trigonal) crystal system.
Appearance:
• transparent to opaque
• almost all colors
Identification:
Optic Character: DR, uniaxial negative; AGG
Refractive Index: 1.486-1.658
Birefringence: .172
Specific Gravity: 2.70 (+-.05)
Hardness: 3 ; Toughness: poor in single crystals, fair to good in aggregates
Stone Information from:
Gem Reference Guide, by GIA, ISBN 0-87311-019-6
Gemstones of the world, Third Edition, by Walter Schumann, ISBN 1-4027-4016-6
https://www.gemdat.org/gem-859.html
https://www.mindat.org/min-859.html