mineral
Tumbled yellow-brown quartz, possibly citrine or iron-stained quartz
Quartz (SiO₂), likely iron-bearing or included variety
AI-generated identification · may be incorrectMohs hardness 7; translucent yellow-brown color, vitreous-to-waxy luster, and massive microcrystalline texture. Quartz lacks cleavage and has conchoidal fracture; the rounded form appears tumbled and wet.
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Physical properties
Mohs hardness 7; translucent yellow-brown color, vitreous-to-waxy luster, and massive microcrystalline texture. Quartz lacks cleavage and has conchoidal fracture; the rounded form appears tumbled and wet.
Formation & geological history
Quartz crystallizes from silica-rich hydrothermal fluids or igneous melts, commonly in veins and cavities. Its yellow-brown color may result from iron impurities or surface staining; age depends on its host deposit.
Uses & applications
Used as a lapidary and decorative stone, with quartz also important in glass, electronics, abrasives, and countertops. This small tumbled piece has modest collector value.
Geological facts
True citrine is naturally yellow quartz, but much commercial “citrine” is heat-treated amethyst; natural color zoning and inclusions can help distinguish them. A scratch test against ordinary glass can support quartz identification, though it may damage the specimen.
Field identification & locations
Commonly found in hydrothermal veins, geodes, and quartz-rich igneous or metamorphic rocks worldwide, especially Brazil, Madagascar, and the United States. Confirm with hardness, streak (white), and ideally refractive index or spectroscopy.
