mineral

Tumbled chalcedony (likely milky quartz)

Microcrystalline quartz, SiO₂; possibly pale agate or quartzite

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent cream-white with faint yellow/brown staining, vitreous to waxy luster, cryptocrystalline structure, and no visible cleavage. Its smoothly rounded shape indicates tumbling or natural abrasion.

Identified August 21, 2026More mineral →

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Physical properties

Formation & geological history

Quartz-rich silica precipitated from groundwater or formed during volcanic, sedimentary, or metamorphic processes; specimens may range from ancient to geologically recent. The exact age and source cannot be determined from the photograph.

Uses & applications

Used as an inexpensive ornamental, lapidary, and jewelry material; polished pieces are sold as pocket stones, beads, and cabochons.

Geological facts

Chalcedony is quartz made of microscopic interlocking crystals, so individual crystal faces are generally absent. Iron staining commonly produces the warm cream-to-yellow coloration.

Field identification & locations

Identify by its glassy/waxy appearance, translucency, lack of cleavage, and ability to scratch ordinary glass; a steel file should not scratch it easily. Common sources include Brazil, Uruguay, India, Madagascar, and the western United States.