mineral

Clear quartz fragment (rock crystal)

Quartz, silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Colorless to smoky-clear, vitreous luster, typically hexagonal crystal structure, no cleavage, and conchoidal fracture; Mohs hardness 7, specific gravity about 2.65. The pictured piece appears irregular and fractured rather than a complete crystal.

Identified August 20, 2026More mineral →

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Physical properties

Formation & geological history

Forms in hydrothermal veins, cavities, pegmatites, and sedimentary/metamorphic rocks when silica-rich fluids crystallize. Quartz is geologically widespread and may range from Precambrian to recent; it is plausible around the Monterrey region, where quartz-bearing veins and sedimentary rocks occur.

Uses & applications

Used extensively in glass, ceramics, abrasives, engineered stone, electronics, and timekeeping; transparent attractive pieces are collected or occasionally used as lapidary material.

Geological facts

Quartz can resemble glass, but it is harder and commonly shows curved conchoidal fractures. It does not have the obvious cleavage of calcite or feldspar.

Field identification & locations

Field tests: it should scratch ordinary glass, resist a steel knife, and leave no powdery streak on unglazed porcelain. Confirmatory identification may require testing because man-made glass can look very similar; the image alone cannot exclude glass with certainty.