Magnetite / Iron Ore

Physical Properties

Hardness: 5.5-6.5 on Mohs scale; Color: Black to silvery gray; Luster: Metallic to submetallic; Crystal Structure: Isometric (often octahedral); Cleavage: None (parting); Specific Gravity: 5.1-5.2 (very heavy).

Formation & Geological History

Formed in igneous, metamorphic, and sedimentary environments. It is often found as an accessory mineral in igneous rocks like basalt and gabbro, or concentrated in hydrothermal veins and banded iron formations.

Uses & Applications

Primary ore of iron; used in heavy media separation, as a pigment in paints (black iron oxide), and in industrial magnetic separators. Higher-grade specimens are sold for educational and mineral collections.

Geological Facts

Magnetite is the most magnetic of all the naturally occurring minerals on Earth. Naturally magnetized pieces are known as lodestones and were used as the first primitive compasses in history.

Field Identification & Locations

Identify in the field by its strong attraction to a magnet and its black streak test. It is significantly heavier than surrounding rocks and often causes local magnetic anomalies. Commonly found in large deposits in Sweden, Australia, and the Lake Superior region of the US.

Identified on: 4/20/2026

Mode: Standard