mineral
Likely tumbled hematite or magnetite
Hematite (Fe₂O₃) or magnetite (Fe₃O₄)
AI-generated identification · may be incorrectSmall rounded, polished black-gray specimen with submetallic luster; likely Mohs hardness 5–6.5, opaque, dense, and lacking visible cleavage or crystal faces. The photograph cannot reliably distinguish hematite from magnetite.
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Physical properties
Small rounded, polished black-gray specimen with submetallic luster; likely Mohs hardness 5–6.5, opaque, dense, and lacking visible cleavage or crystal faces. The photograph cannot reliably distinguish hematite from magnetite.
Formation & geological history
These iron oxides form in hydrothermal, igneous, metamorphic, and sedimentary environments; magnetite commonly crystallizes in igneous rocks, while hematite often forms by oxidation or precipitation. Geological ages vary widely.
Uses & applications
Used as iron ore, pigment, and decorative or metaphysical material; polished pieces are inexpensive collectibles. Magnetite is strongly magnetic, whereas hematite is usually weakly magnetic or nonmagnetic.
Geological facts
A strong attraction to a magnet favors magnetite; a reddish-brown streak favors hematite. The smooth shape indicates tumbling or natural abrasion rather than a diagnostic crystal form.
Field identification & locations
Test with a magnet, streak it on unglazed porcelain, and compare density: hematite leaves a red-brown streak, while magnetite leaves a black streak and is strongly magnetic. Common sources include iron-ore regions worldwide.
