Rock Identifier
Tumbled milky quartz pebble (Quartz (silicon dioxide, SiO₂), likely milky quartz) — mineral
mineral

Tumbled milky quartz pebble

Quartz (silicon dioxide, SiO₂), likely milky quartz

AI-generated identification · may be incorrect

White to cream, translucent-to-opaque, vitreous to waxy luster, rounded by tumbling; Mohs hardness 7, no cleavage, conchoidal fracture, hexagonal crystal structure. The yellow patches may be iron staining or surface discoloration.

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Physical properties

White to cream, translucent-to-opaque, vitreous to waxy luster, rounded by tumbling; Mohs hardness 7, no cleavage, conchoidal fracture, hexagonal crystal structure. The yellow patches may be iron staining or surface discoloration.

Formation & geological history

Quartz formed in hydrothermal veins, pegmatites, or weathered igneous and metamorphic rocks; natural specimens range from Precambrian to recent, while this piece has been mechanically polished. Common sources include Brazil, Madagascar, the United States, and India.

Uses & applications

Used for decorative stones, countertops, abrasives, glass, and electronics; attractive translucent pieces are sold as lapidary or collector material.

Geological facts

Milky appearance results from microscopic fluid inclusions, fractures, or mineral impurities that scatter light. Quartz is one of Earth’s most abundant and durable minerals.

Field identification & locations

Identify it by its glassy appearance, lack of cleavage, hardness sufficient to scratch ordinary glass, and conchoidal breakage; a steel knife should not scratch it. A definitive ID may require testing because calcite, marble, or man-made ceramic can look similar.