mineral

Magnetite (Lodestone)

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Iron-black to dark grey; Luster: Metallic to sub-metallic; Crystal Structure: Isometric (often octahedral); Cleavage: None (distinct parting in some specimens); Specific Gravity: 5.1-5.2

Hardness: 5
Color: Iron-black to dark grey
Luster: Metallic to sub-metallic

Identified March 16, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous, metamorphic, and sedimentary environments. Typically occurs as an accessory mineral in igneous rocks like basalt and gabbro, or in banded iron formations resulting from oxygenation events billions of years ago.

Uses & applications

Primary ore of iron; used in heavy media separation, industrial catalysts, and as a magnetic pigment. Historically used as a primitive compass. Some specimens are polished for jewelry or metaphysical use.

Geological facts

Magnetite is the most magnetic mineral on Earth. Naturally magnetized pieces are called lodestones. It was used by the Vikings and other early navigators to create the first compasses by suspending a piece of lodestone on a string.

Field identification & locations

Identify in the field using a strong magnet; the specimen will be strongly attracted to it. It leaves a black streak on a porcelain plate and is significantly heavier than non-metallic rocks of the same size. Found globally in places like Sweden, Brazil, and the Lake Superior region of North America.