igneous
Tumbled black stone, likely basalt or black jasper
Probably basalt (fine-grained plagioclase–pyroxene rock); exact identification is uncertain from the image
AI-generated identification · may be incorrectSmall, smooth, oval, opaque black specimen with a subdued vitreous-to-waxy luster and scattered pale specks. Likely Mohs hardness 5–6; no visible cleavage; basalt is fine-grained and commonly dense, with specific gravity about 2.8–3.0.
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Physical properties
Small, smooth, oval, opaque black specimen with a subdued vitreous-to-waxy luster and scattered pale specks. Likely Mohs hardness 5–6; no visible cleavage; basalt is fine-grained and commonly dense, with specific gravity about 2.8–3.0.
Formation & geological history
If basalt, it formed when iron- and magnesium-rich lava cooled rapidly at or near Earth’s surface, commonly in volcanic flows; ages range from modern to billions of years. If jasper, it is microcrystalline quartz formed from silica-rich fluids or sediment.
Uses & applications
Used as a decorative tumbled stone, paperweight, or low-cost craft material; basalt is widely used for aggregate, paving, and construction, while jasper is used in cabochons and ornaments.
Geological facts
The smooth shape indicates tumbling or water abrasion rather than a naturally crystal-faced specimen. Pale dots may be feldspar, weathering products, or inclusions.
Field identification & locations
Check for tiny interlocking grains, magnetic response, and hardness: basalt may weakly attract a magnet and resist a steel knife; jasper typically scratches glass and has a waxier appearance. Common sources include volcanic regions worldwide.
