mineral

Magnetite sand (black iron-oxide sand)

Magnetite, Fe₃O₄; commonly mixed with ilmenite and other heavy minerals

AI-generated identification · may be incorrect

Black to steel-gray, opaque, metallic to submetallic luster; Mohs hardness 5.5–6.5, cubic crystal structure, no prominent cleavage, specific gravity about 5.2. Strongly magnetic, often appearing as fine granules.

Identified August 19, 2026More mineral →

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Physical properties

Formation & geological history

Forms through weathering and erosion of magnetite-bearing igneous and metamorphic rocks, with wave or stream action concentrating dense grains into placer deposits. Its mineral grains may range from Precambrian to recent geological ages.

Uses & applications

Used as an iron ore, dense aggregate, radiation-shielding or drilling-mud additive, pigment, and educational or collectible material; not typically used as jewelry in granular form.

Geological facts

Magnetite is one of the most strongly magnetic common minerals and can become naturally magnetized as lodestone. The image shows loose granular material rather than a coherent rock.

Field identification & locations

Confirm with a strong magnet: grains should attract readily; a streak test gives a black streak. Common along volcanic beaches and river placers, including New Zealand, Japan, Hawaii, India, and parts of the United States.