Rock Identifier
Black drusy mineral coating, possibly hematite or manganese oxide (Undetermined; likely microcrystalline hematite (Fe₂O₃) or manganese oxides such as pyrolusite (MnO₂)) — mineral
mineral

Black drusy mineral coating, possibly hematite or manganese oxide

Undetermined; likely microcrystalline hematite (Fe₂O₃) or manganese oxides such as pyrolusite (MnO₂)

AI-generated identification · may be incorrect

Black, sparkly granular surface with a dull to submetallic luster; individual crystals appear very fine and botryoidal/drusy. Hardness is likely about 5–6.5 for hematite or 6–6.5 for pyrolusite, but the image is insufficient for reliable identification; cleavage and specific gravity are unavailable.

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Physical properties

Black, sparkly granular surface with a dull to submetallic luster; individual crystals appear very fine and botryoidal/drusy. Hardness is likely about 5–6.5 for hematite or 6–6.5 for pyrolusite, but the image is insufficient for reliable identification; cleavage and specific gravity are unavailable.

Formation & geological history

Likely formed as an oxidation-zone coating or cavity lining in a mineralized host rock, where iron or manganese-rich fluids precipitated microscopic crystals. Its geological age cannot be determined from the photograph.

Uses & applications

Primarily a decorative or collector specimen; hematite and manganese minerals have industrial importance as iron or manganese ores, but this textured piece is unlikely to have commercial value.

Geological facts

The glitter may come from thousands of tiny crystal faces rather than metallic flakes. A streak test is especially useful: hematite generally leaves a red-brown streak, while manganese oxides commonly leave a black to dark-brown streak.

Field identification & locations

Commonly found in iron- and manganese-rich deposits worldwide, including Brazil, Morocco, South Africa, and the western United States. Test streak, magnetism, hardness, and specific gravity; avoid assuming it is obsidian or coal from appearance alone.