mineral
Polished black stone, likely hematite
Hematite (Fe₂O₃), possibly black jasper or basalt
AI-generated identification · may be incorrectSmall rounded, tumbled specimen with metallic-to-submetallic dark-gray luster and smooth surface; hematite has Mohs hardness 5–6.5, no obvious cleavage, trigonal crystal structure, and specific gravity about 5.3.
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Physical properties
Small rounded, tumbled specimen with metallic-to-submetallic dark-gray luster and smooth surface; hematite has Mohs hardness 5–6.5, no obvious cleavage, trigonal crystal structure, and specific gravity about 5.3.
Formation & geological history
If hematite, it formed through oxidation and precipitation of iron-bearing fluids or sediments, commonly in Precambrian banded iron formations. The image alone cannot establish geological age or distinguish it confidently from other polished dark stones.
Uses & applications
Used as an iron ore, pigment, and ornamental tumbled stone; common specimens generally have modest collector value.
Geological facts
A diagnostic hematite test is a reddish-brown to red streak on unglazed porcelain, even when the specimen itself appears black. Strong magnetism would suggest magnetite rather than ordinary hematite.
Field identification & locations
Common sources include Brazil, Australia, the United States, and South Africa. Field identification requires streak, magnetism, density, and ideally chemical testing; visual identification here is uncertain.
