Rock Identifier
Likely polished dark metallic mineral specimen (Indeterminate from image; possibly hematite, magnetite, or galena) — mineral
mineral

Likely polished dark metallic mineral specimen

Indeterminate from image; possibly hematite, magnetite, or galena

AI-generated identification · may be incorrect

Small irregular specimen with black-to-silver metallic luster and reflective surfaces; hardness and cleavage cannot be reliably determined visually. Galena would have cubic cleavage and Mohs hardness 2.5, hematite 5–6.5, and magnetite 5.5–6.5.

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Physical properties

Small irregular specimen with black-to-silver metallic luster and reflective surfaces; hardness and cleavage cannot be reliably determined visually. Galena would have cubic cleavage and Mohs hardness 2.5, hematite 5–6.5, and magnetite 5.5–6.5.

Formation & geological history

These minerals commonly form in hydrothermal veins or iron-rich igneous and metamorphic environments; their ages range widely from Precambrian to recent geological deposits.

Uses & applications

Used mainly for collecting; hematite and magnetite are iron ores, while galena is a lead ore. Polished pieces may be sold as display specimens or cabochons.

Geological facts

A streak test and magnet test are especially useful: hematite gives a reddish-brown streak, magnetite is strongly magnetic with a black streak, and galena gives a gray-black streak and is unusually dense.

Field identification & locations

Common sources include Brazil, Mexico, the United States, Peru, and Morocco. Confirm identification using streak, magnetism, specific gravity, and cleavage; the image alone is insufficient for a precise species identification.