igneous
Smoky Quartz on Feldspar (Granite Pegmatite)
Silicon Dioxide (SiO2) with Potassium Aluminum Silicate (KAlSi3O8)
Hardness: 6 (Feldspar) to 7 (Quartz); Color: Smoked-grey crystals on tan/orange host rock; Luster: Vitreous to pearly; Crystal structure: Trigonal (quartz) and Monoclinic (feldspar).
- Hardness
- 6 (Feldspar) to 7 (Quartz)
- Color
- Smoked-grey crystals on tan/orange host rock
- Luster
- Vitreous to pearly
Identified More igneous →
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Physical properties
Hardness: 6 (Feldspar) to 7 (Quartz); Color: Smoked-grey crystals on tan/orange host rock; Luster: Vitreous to pearly; Crystal structure: Trigonal (quartz) and Monoclinic (feldspar).
Formation & geological history
Formed in high-silica magma during the slow cooling and crystallization of igneous intrusions, specifically in pegmatite pockets. Age varies globally from Precambrian to Cenozoic.
Uses & applications
Quartz is used in glassmaking and electronics; feldspar is used in ceramics and glass; high-quality specimens are used for mineral collecting and lapidary arts.
Geological facts
Smoky quartz gets its color from natural irradiation of aluminum-bearing quartz. Darker varieties can be so dark they are opaque, commonly referred to as 'Morion'.
Field identification & locations
Identify by looking for vitreous, smoky grey crystals growing out of a more opaque, blocky orange or white mineral matrix. Common in mountainous regions like the Rockies or Alps.
