Hematite (beads)

Hardness: 5.5-6.5 on Mohs scale; Color: Metallic gray to black (in massive form, often reddish-brown streak); Luster: Metallic, submetallic to dull; Crystal Structure: Trigonal; Cleavage: None (parting common); Specific Gravity: 5.26 g/cm3. The beads in the image exhibit a polished, metallic luster.

Hematite is a common iron oxide mineral that forms in a wide variety of geological environments. It can form as a primary mineral during magmatic differentiation, hydrothermal activity, and contact metamorphism. It is also a significant component of banded iron formations (BIFs), which are Precambrian sedimentary rocks. It forms through precipitation from water, weathering of iron-rich rocks, and oxidation of other iron minerals.

Hematite is the most important ore of iron, used extensively in steel production. Polished hematite is used in jewelry (like the beads shown), ornamental objects, and sculptures. Its dense nature makes it useful as a weighting agent in drilling muds. It is also used as a pigment (red ochre) and as an abrasive.

The name Hematite comes from the Greek word "haima" meaning blood, referring to its reddish streak. It is responsible for the red color of many rocks and soils, and also the red color of the surface of Mars. Hematite can be weakly magnetic, but is not considered a true ferromagnet. The iridescent varieties are sometimes called 'rainbow hematite'.

In the field, hematite can be identified by its distinctive reddish-brown streak, which is always consistent regardless of the specimen's external color. Its metallic luster and high density are also good indicators. It does not react to acid. It is commonly found in sedimentary deposits like banded iron formations, hydrothermal veins, and weathered igneous/metamorphic rocks. Tips for collectors: Test the streak on an unglazed porcelain plate. Larger, well-formed crystals are sought after. The beads in the image are clearly manufactured items from polished hematite.