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