mineral
Polished/tumbled brown jasper (likely weathered chert)
Microcrystalline quartz, SiO₂, with iron-oxide impurities
AI-generated identification · may be incorrectOpaque caramel-brown to golden brown, waxy to dull luster, uneven mottled texture, and no visible cleavage; quartz hardness is about 6.5–7 Mohs, with specific gravity near 2.6. The rounded shape indicates human tumbling or polishing.
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Physical properties
Opaque caramel-brown to golden brown, waxy to dull luster, uneven mottled texture, and no visible cleavage; quartz hardness is about 6.5–7 Mohs, with specific gravity near 2.6. The rounded shape indicates human tumbling or polishing.
Formation & geological history
Forms when silica-rich fluids replace or cement sediment, commonly producing microcrystalline quartz with iron staining; alteration may occur in sedimentary volcanic environments over broad geological ages. Exact age and locality cannot be determined from the image.
Uses & applications
Used as a lapidary stone for cabochons, carvings, beads, and decorative objects; also collected as an attractive common jasper variety.
Geological facts
Jasper is a chalcedony-related variety of quartz, but unlike translucent agate it is generally opaque because of abundant impurities. The specimen may also be silicified wood or another iron-stained chert, which requires testing to distinguish.
Field identification & locations
Check for a glassy conchoidal fracture, quartz-like hardness, and inability to scratch with a steel knife; jasper typically leaves a white streak. Common sources include India, Madagascar, Brazil, the United States, and Australia.
