mineral

Magnetite (Lodestone variant)

Magnetite (Fe3O4)

Hardness: 5.5-6.5 Mohs scale; Color: Black, iron-black to dark grey; Luster: Metallic to submetallic; Crystal Structure: Isometric/Octahedral; Cleavage: None (distinct parting in some specimens); Specific Gravity: 5.17-5.18.

Hardness: 5
Color: Black, iron-black to dark grey
Luster: Metallic to submetallic

Identified June 8, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Magnetite is commonly found in igneous rocks such as basalt and gabbro, and in metamorphic rocks like greenschists. It forms via magmatic crystallization or precipitation from hydrothermal fluids. Some forms as a beach sand (black sand) via weathering and erosion.

Uses & applications

Magnetite is a major ore of iron used in steel production. It is used as an abrasive (emery), in heavy media separation for coal washing, and as a component in magnetic storage media. High-quality specimens are popular among mineral collectors.

Geological facts

Magnetite is the most magnetic of all the naturally occurring minerals on Earth. Naturally magnetized pieces called lodestones were used as the earliest form of magnetic compasses. It is responsible for the paleomagnetism records in oceanic crust that helped prove plate tectonics.

Field identification & locations

Can be identified in the field by its black streak on a porcelain plate and its strong attraction to magnets. Check for its high density and metallic luster. It is commonly found in iron mines and areas with volcanic activity.