mineral
Smoky quartz with feldspar matrix
Quartz (SiO₂), likely intergrown with potassium feldspar and mica
AI-generated identification · may be incorrectTranslucent to transparent smoky-brown quartz with vitreous luster, uneven fracture, and probable hexagonal crystal structure; Mohs hardness 7. The pale cream material is likely feldspar, with minor dark mica or iron staining.
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Physical properties
Translucent to transparent smoky-brown quartz with vitreous luster, uneven fracture, and probable hexagonal crystal structure; Mohs hardness 7. The pale cream material is likely feldspar, with minor dark mica or iron staining.
Formation & geological history
Formed in a granitic pegmatite or hydrothermal vein as silica-rich fluids cooled and crystallized, typically during Precambrian to Phanerozoic intrusive activity. Smoky coloration commonly results from irradiation affecting aluminum impurities in quartz.
Uses & applications
Used as a collector specimen; clear portions may be cut as gemstones, while quartz is widely used in glass, ceramics, abrasives, electronics, and construction aggregate.
Geological facts
Smoky quartz ranges from pale gray-brown to nearly black (“morion”); its color can fade with strong heat or sunlight. Feldspar inclusions and matrix indicate this is a natural, uncut mineral fragment.
Field identification & locations
Identify by glassy luster, conchoidal fracture, lack of cleavage, and resistance to scratching with a steel file; feldspar shows two cleavage directions and is softer. Common in granite pegmatites worldwide, especially Brazil, the United States, Switzerland, and Madagascar.
