mineral
Likely graphite-rich ore or galena-bearing rock
Graphite (C) or galena (PbS), identification uncertain from photograph
AI-generated identification · may be incorrectDark gray to black, strongly metallic-looking, irregular granular mass with reflective cleavage faces. Graphite is very soft (Mohs 1–2), greasy, and marks paper; galena is harder (Mohs 2.5–3), exceptionally dense, and has cubic cleavage.
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Physical properties
Dark gray to black, strongly metallic-looking, irregular granular mass with reflective cleavage faces. Graphite is very soft (Mohs 1–2), greasy, and marks paper; galena is harder (Mohs 2.5–3), exceptionally dense, and has cubic cleavage.
Formation & geological history
Graphite forms through metamorphism of carbon-rich sediments or in igneous veins; galena forms mainly in hydrothermal sulfide veins. A precise age and origin require locality and testing.
Uses & applications
Graphite is used in lubricants, refractories, batteries, and pencils; galena is an important lead ore and may contain silver. Neither is typically used as a gemstone.
Geological facts
A streak test, density measurement, and cleavage examination are highly diagnostic: graphite leaves a black streak and feels greasy, while galena commonly breaks into cubic fragments and feels unusually heavy.
Field identification & locations
Common graphite localities include Sri Lanka, Madagascar, China, and metamorphic terrains worldwide; galena is widespread in hydrothermal mining districts. Do not handle or grind suspected galena without precautions because lead sulfide is toxic.
