mineral

Tumbled quartz (rock crystal)

Quartz, silicon dioxide (SiO₂)

AI-generated identification · may be incorrect

Colorless to milky white, translucent, with a vitreous luster and irregular conchoidal fractures; Mohs hardness 7, trigonal crystal structure, no cleavage, and specific gravity about 2.65. The rounded shape indicates tumbling or natural abrasion.

Identified August 21, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystallizes from silica-rich hydrothermal fluids, igneous melts, and sedimentary systems across much of geologic time; this specimen’s exact age and locality cannot be determined visually. Milky appearance results from microscopic fluid inclusions or fractures.

Uses & applications

Used in glass, ceramics, electronics, abrasives, engineered stone, and jewelry; tumbled pieces are mainly sold as inexpensive decorative or metaphysical stones.

Geological facts

Quartz is one of Earth’s most abundant minerals and is piezoelectric, producing an electrical charge under mechanical stress. It commonly forms in granite, pegmatites, veins, and quartz-rich sedimentary rocks.

Field identification & locations

Identify by its glassy appearance, hardness, lack of cleavage, and inability to scratch it with a steel knife; it should scratch ordinary glass. Common worldwide, especially in Brazil, the United States, Madagascar, and China.