mineral

Magnetite Sand (Black Sand)

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Iron-black to brownish-black; Luster: Metallic to submetallic; Crystal Structure: Isometric/Octahedral; Opaque and strongly magnetic.

Hardness: 5
Color: Iron-black to brownish-black
Luster: Metallic to submetallic

Identified July 15, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5; Color: Iron-black to brownish-black; Luster: Metallic to submetallic; Crystal Structure: Isometric/Octahedral; Opaque and strongly magnetic.

Formation & geological history

Magnetite is a common accessory mineral in igneous and metamorphic rocks. As these rocks weather, the heavy magnetite crystals resist chemical breakdown and accumulate as 'black sand' in riverbeds or coastal deposits through alluvial action.

Uses & applications

Major ore of iron; used in heavy-media separation, as a pigment (mars black), and in industrial abrasives. In this granular form, it is often collected for scientific study or iron extraction.

Geological facts

Magnetite is the most magnetic naturally occurring mineral on Earth. Small grains like these were historical precursors to the compass when found as 'lodestones'. The location provided (Ethiopian Highlands area) is known for volcanic rocks like basalt, which frequently weather into magnetite-rich soils and sands.

Field identification & locations

Identify by using a magnet; the grains will readily cling to it. In the field, look for dark, heavy streaks in riverbeds. Collectors value high-purity samples or those with visible octahedral crystal shapes.