mineral

Tumbled quartz-rich pebble

Quartz (SiO₂), likely with iron-oxide staining and minor feldspar

AI-generated identification · may be incorrect

Hardness about 7 Mohs; cream, tan, and rusty-brown color; vitreous to dull luster; massive granular texture with no obvious cleavage. The rounded shape indicates tumbling or natural water abrasion; specific gravity is approximately 2.65.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystallized in igneous or hydrothermal rocks and was later liberated by weathering and rounded by transport or tumbling. Quartz is mostly Precambrian to recent in source rocks, so the specimen’s exact age cannot be determined visually.

Uses & applications

Used as a decorative pebble, lapidary material, aggregate, and silica source; generally unsuitable for faceted jewelry unless a clearer portion is present.

Geological facts

Brown coloration commonly comes from hydrated iron oxides such as limonite or hematite. The cloudy appearance reflects microscopic inclusions, fractures, and/or intergrown feldspar.

Field identification & locations

Identify by its glassy fracture, lack of cleavage, white streak, and ability to scratch ordinary glass; a steel blade should not scratch it. Common in quartz veins, granitic terrains, river gravels, and glacial deposits worldwide.