mineral
Polished smoky quartz crystal with inclusions
Quartz, silicon dioxide (SiO₂), likely smoky quartz with iron-oxide or other mineral inclusions
AI-generated identification · may be incorrectMohs hardness 7; translucent gray-brown to nearly clear, with vitreous luster and conchoidal fracture. Hexagonal quartz structure; the apparent flat base and pointed top indicate it was cut or shaped rather than naturally terminated.
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Physical properties
Mohs hardness 7; translucent gray-brown to nearly clear, with vitreous luster and conchoidal fracture. Hexagonal quartz structure; the apparent flat base and pointed top indicate it was cut or shaped rather than naturally terminated.
Formation & geological history
Quartz crystallizes from silica-rich hydrothermal fluids in cavities of igneous and metamorphic rocks, commonly during the Paleozoic–Cenozoic; exact age cannot be determined from the image.
Uses & applications
Used as a collector specimen, ornamental stone, and occasionally in jewelry; included quartz is generally more decorative than gem-grade.
Geological facts
The dark smoky color commonly results from radiation-induced color centers associated with aluminum impurities; heating can partially remove the color.
Field identification & locations
Identify by its glassy luster, hardness, lack of obvious cleavage, and hexagonal crystal habit; common sources include Brazil, Madagascar, Switzerland, and the United States. The inclusions may also indicate tourmaline, mica, or iron oxides, but visual confirmation is insufficient.
