mineral
Magnetite-rich iron ore
Magnetite (Fe₃O₄), possibly mixed with hematite or metallic sulfides
AI-generated identification · may be incorrectBlack to steel-gray, submetallic-to-metallic luster, irregular massive texture, and high density (specific gravity about 5.2). Magnetite has Mohs hardness 5.5–6.5 and is strongly magnetic; crystal structure is cubic, though this specimen is not visibly crystalline.
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Physical properties
Black to steel-gray, submetallic-to-metallic luster, irregular massive texture, and high density (specific gravity about 5.2). Magnetite has Mohs hardness 5.5–6.5 and is strongly magnetic; crystal structure is cubic, though this specimen is not visibly crystalline.
Formation & geological history
Forms mainly in igneous and metamorphic iron deposits, hydrothermal veins, and banded iron formations, ranging from Precambrian to recent geological ages. The specimen appears naturally weathered and massive rather than a manufactured material.
Uses & applications
Magnetite is an important iron ore and is used in steel production, dense concrete, pigments, and magnetic applications; attractive specimens have modest collecting value.
Geological facts
Its defining feature is strong attraction to a magnet, often stronger than ordinary dark rocks. A gray-black streak and unusually heavy feel further support identification.
Field identification & locations
Test with a strong magnet, streak it on unglazed porcelain, and compare its weight with similarly sized rocks; magnetite leaves a black streak, whereas hematite leaves red-brown. Common sources include banded iron formations and volcanic or metamorphic terrains worldwide.
