mineral
Polished dark gemstone, likely hematite or magnetite
Hematite (Fe₂O₃) or magnetite (Fe₃O₄); exact identification requires testing
AI-generated identification · may be incorrectSmall polished black-to-silver, opaque stone with metallic luster and irregular cabochon-like shape. Hematite has Mohs hardness 5–6.5 and red-brown streak; magnetite has hardness 5.5–6.5 and is strongly magnetic; both are commonly dense and non-cleaving.
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Physical properties
Small polished black-to-silver, opaque stone with metallic luster and irregular cabochon-like shape. Hematite has Mohs hardness 5–6.5 and red-brown streak; magnetite has hardness 5.5–6.5 and is strongly magnetic; both are commonly dense and non-cleaving.
Formation & geological history
Iron oxides form in hydrothermal, magmatic, metamorphic, and sedimentary environments over a wide range of geological ages. Polishing and mounting in a ring are human processing, but the material remains geological.
Uses & applications
Used for jewelry, ornamental objects, pigments, and iron ore; hematite jewelry is especially common. Magnetite is primarily an industrial iron ore and is less commonly cut for jewelry.
Geological facts
A strong magnet, especially attraction through the setting, favors magnetite; a red or reddish-brown streak on unglazed porcelain favors hematite. The photograph alone cannot reliably distinguish them from other dark opaque minerals.
Field identification & locations
Common sources include Brazil, Australia, South Africa, India, and the United States. Check streak, magnetism, density, and hardness; avoid scratching the mounted stone.
