Smoky Quartz
Image: Rob Lavinsky (CC BY 3.0)
Mineral NameSmoky Quartz
Chemical FormulaSiO2
Mohs Hardness7
Crystal Systemtrigonal
Lustervitreous
Streak Colorwhite
Cleavagenone
Fractureconchoidal
Specific Gravity2.65
Colorsbrown, grey-brown, black
Transparencytransparent
Type LocalityNew Mexico, USA
Mineral GroupSilicates
Usesjewelry, collector, industrial
Associated Mineralsfeldspar, mica, topaz, beryl
Raritycommon
Description
This specimen features an unusually well-balanced, totally gemmy, pristine, and incredibly sharply terminated central crystal on matrix, with superb equant form. It exhibits a dark, smoky color and a sharp internal phantom, which is rare for its location.
Geological Context
Smoky quartz forms in igneous and metamorphic rocks, as well as hydrothermal veins, often due to natural irradiation of aluminum-bearing quartz. It is commonly found in granites, pegmatites, and certain volcanic rocks.
