Quartz (Rock Crystal)

Physical Properties

Hardness: 7.0 on Mohs scale; Color: Colorless to white; Luster: Vitreous (glassy); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & Geological History

Forms in a wide variety of environments including igneous (granite), metamorphic (quartzite), and sedimentary rocks. It crystallizes from silica-rich hydrothermal fluids or cooling magma.

Uses & Applications

Used in electronics (oscillators), optics, abrasives, glassmaking, and frequently as a gemstone or for decorative collecting.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. It is piezo-electric, meaning it can generate an electrical charge in response to mechanical stress.

Field Identification & Locations

Identify by its ability to scratch glass and lack of cleavage. Often found near granite outcrops, in riverbeds, or as veins within larger rock bodies. Very common worldwide.

Identified on: 5/19/2026

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