mineral

Polished hematite (likely hematite-rich ironstone)

Hematite, Fe₂O₃; possibly mixed with magnetite or jasper

AI-generated identification · may be incorrect

The rounded polished specimen is dark gray to black with a metallic to submetallic reflective luster and reddish-brown edge tones. Hematite has Mohs hardness 5–6.5, trigonal crystal structure, no prominent cleavage, and specific gravity about 5.0–5.3; a red-brown streak is diagnostic.…

Identified September 19, 2026More mineral →

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Physical properties

Formation & geological history

Hematite forms through oxidation of iron-bearing minerals, hydrothermal activity, or chemical sedimentation, commonly in Precambrian banded iron formations and ironstone. The visible piece has been cut and tumbled/polished, so its precise age and source cannot be determined.

Uses & applications

Used as an iron ore, pigment, polishing medium, and ornamental stone. Polished hematite is common in inexpensive jewelry and worry stones.

Geological facts

A strong red-to-reddish-brown streak on unglazed porcelain distinguishes hematite from similarly shiny magnetite. It is weakly to nonmagnetic, whereas magnetite is strongly magnetic.

Field identification & locations

Likely identification: polished hematite or hematite-rich ironstone. Test the streak and magnetism; hematite commonly occurs in iron-rich rocks worldwide, including California, though the image alone cannot establish a local source near 38.7°N, 121.3°W.