Hematite

Hardness 5.5-6.5, metallic to earthy luster, opaque, often steel-gray to black or red-brown color. High specific gravity.

Forms in diverse environments including sedimentary, igneous, and metamorphic rocks. Often formed by the weathering of iron-bearing minerals or precipitation in banded iron formations.

Primary ore of iron. Used in jewelry, polishing compounds, and as a pigment (red ochre).

Leaves a characteristic red or reddish-brown streak, which is a key diagnostic feature despite its metallic gray appearance.

Identified by its red streak and high density. Commonly found worldwide, notably in banded iron formations.