mineral

Psilomelane (Black Hematite/Manganese Ore)

Barium Manganese Oxide (Formula: BaMn9O18(OH)4)

Hardness: 5-6 (Mohs scale); Color: Black to dark gray; Luster: Submetallic, dull, or silky; Crystal Structure: Monoclinic (usually found in botryoidal or massive forms); Cleavage: None; Specific Gravity: 3.7 - 4.7

Hardness: 5-6 (Mohs scale)
Color: Black to dark gray
Luster: Submetallic, dull, or silky

Identified March 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral through the weathering and oxidation of primary manganese minerals. Often found in hydrothermal veins and sedimentary deposits where manganese has precipitated from water. It dates across various geological ages, often associated with Precambrian formations.

Uses & applications

Primary source of manganese ore for steel manufacturing; also used as a pigment in glass and ceramics. Polished specimens are often used as cabochons in semi-precious jewelry or collected for their unique botryoidal patterns.

Geological facts

Commonly known as 'black hematite' even though it contains no iron. The name is derived from the Greek words 'psilos' (smooth) and 'melas' (black), referring to its smooth, rounded, dark exterior. It is often found associated with minerals like pyrolusite and goethite.

Field identification & locations

Identify in the field by its black streak, botryoidal (grape-like) habit or radiating fibrous internal structure, and its relatively high density. Found at major deposits in Germany, India, Brazil, and the United States (Lake Superior region and Manganese Island). Collectors look for 'silver lace' patterns when sliced.

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