mineral

Tumbled magnetite (likely)

Magnetite, Fe₃O₄

AI-generated identification · may be incorrect

Small polished black specimen with a submetallic to metallic luster and a rusty-gold reflective vein or coating; magnetite has Mohs hardness 5.5–6.5, black streak, cubic crystal structure, and no prominent cleavage. The visible vein makes identification uncertain from the image alone.

Identified September 19, 2026More mineral →

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Physical properties

Formation & geological history

Magnetite forms in igneous and metamorphic rocks, hydrothermal veins, and banded iron formations, ranging from Precambrian to recent deposits. This piece appears human-tumbled or polished.

Uses & applications

Used as an iron ore, dense aggregate, pigment, and magnetic material; attractive pieces are collected, though it is not generally a jewelry gemstone.

Geological facts

Magnetite is strongly magnetic and commonly attracts a magnet; its name comes from its magnetic behavior. A rusty-gold surface may represent oxidation or another mineral vein, such as pyrite.

Field identification & locations

Test with a strong magnet, inspect the black streak on unglazed ceramic, and compare density (about 5.2 g/cm³). Common sources include Sweden, Australia, South Africa, the United States, and Brazil.