Smoky Quartz
- Quartz species; hexagonal (trigonal) crystal system; chemical composition SiO2
- Smoky Quartz – transparent light to dark brown; sometimes nearly opaque black (called morion)
Identification:
- Optic Character: DR uniaxial positive or AGG (depending on variety)
- Refractive Index: 1.544-1.553 (very constant)
- Birefringence: .009 (may not be detectable in aggregate varieties) Dispersion: .013
- Pleochroism: weak brown and reddish brown in dark stones; light and darker yellow
- Cause of Color: smoky quartz – color centers involving aluminum impurities and irradiation (natural or artificial)
- Specific Gravity: 2.66 (+.03.-.02)
- Hardness: 7
- Toughness: good.
Enhancements:
- Method: irradiation
Effect: produces smoky quartz from rock crystal; intensifies the color of rose quartz
Prevalence: common in crystal specimens of smoky quartz; occasional in rose quartz
Detection: undetectable
Stability: excellent
- Method: heat treatment
Effect: lightens color of very dark smoky quartz; produces green quartz from some amethyst
Prevalence: occasional
Detection: undetectable
Stability: excellent
Birthstone Designation(s):
Smoky Quartz – November, 1:00 am
Major Source: Brazil.
Stone information is reference from
Gem Reference Guide, Published by GIA. ISBN 0-87311-019-6
Gemstones of the World, Published by Sterling Publishing Co., Inc NY, ISBN 1-4027-4016-6
Encyclopedia of GEMSTONE, Published by ISHINSHA CO., LTD. ISBN 978-986-251-831-1
