Hematite

Hardness: 5-6.5; Color: Steel gray to silver-white, earthy red to reddish-brown; Luster: Metallic to dull/earthy; Crystal structure: Trigonal; Cleavage: None (has parting); Specific gravity: 5.26

Hematite forms in a wide variety of geological environments. It can precipitate from water in layered sedimentary deposits (banded iron formations), form as a primary mineral in igneous and metamorphic rocks, or result from hydrothermal activity or weathering of other iron-bearing minerals. Many significant deposits are Precambrian in age, related to vast oceanic processes.

Hematite is the most important ore of iron, used extensively in the steel industry. Finely powdered hematite is also used as a polishing agent (jeweler's rouge), a red pigment (ocker), and in radiation shielding. Due to its attractive metallic luster and range of colors, it is also used in jewelry and ornamental carvings.

The name Hematite comes from the Greek word 'haima,' meaning blood, referring to the reddish color of its powder or streak. It is responsible for the red color of many rocks and soils worldwide, including the coloration of Mars, giving the planet its 'red planet' nickname.

Hematite is identified by its characteristic reddish-brown streak, regardless of its external color (which can be gray or silver). It is non-magnetic, though some varieties like specular hematite can be slightly magnetic due to inclusions of magnetite. It often occurs as botryoidal (kidney-like) masses, tabular crystals, or earthy aggregates. Commonly found in sedimentary iron formations, hydrothermal veins, and weathered igneous/metamorphic rocks. Collectors look for well-formed crystals or botryoidal specimens.