How to Identify Magnetite: Properties & Lookalikes

Black metallic magnetite crystal specimen — Magnetite crystal specimen; source image resized and re-encoded for web displayPhoto: Robert M. Lavinsky · CC BY-SA 3.0 · Wikimedia Commons

Classification

What is magnetite?

Magnetite contains both ferrous and ferric iron. Titanium and other elements can substitute, and intergrowths with related oxides may affect magnetic behavior.

Appearance

What does magnetite look like?

Magnetite forms octahedral crystals, granular aggregates, massive layers, and disseminated grains. Fresh surfaces are black with metallic to dull luster.

Weathering can replace magnetite with hematite, maghemite, goethite, or mixtures, producing rusty surfaces and weaker magnetism.

Field tests

Identification tests

Begin with observation and use the least destructive test first. Results can change with weathering, mixtures, coatings, and grain size. Review the step-by-step field-test methods before altering an unfamiliar specimen.

Magnetism

Strong attraction to a hand magnet

The key field property; test several parts of mixed rock.

Streak

Black

Separates magnetite from red-streaking hematite.

Hardness

5.5 to 6.5

Harder than many black oxides and most weathered coatings.

Density

Noticeably heavy for size

Supports an iron-rich mineral but is not unique.

Useful procedures: Mineral magnetism test · Mineral streak test · Mohs hardness test · Specific gravity and density test

Comparison

Common lookalikes

Hematite

Leaves a red-brown streak and is ordinarily much less magnetic.

Ilmenite

Has a black streak but is usually only weakly magnetic unless altered or intergrown.

Industrial slag

May be magnetic but commonly shows bubbles, glassy textures, or furnace context.

Geologic origin

How does it form?

Magnetite crystallizes from magma, develops during metamorphism, forms in hydrothermal systems, and accumulates as heavy grains in sediment.

It can occur as an accessory mineral or dominate iron-rich layers and ore bodies. Geological context determines significance.

Where it occurs

Geologic setting and occurrence

Magnetite occurs in many igneous and metamorphic rocks, iron formations, skarns, black sands, and some hydrothermal deposits.

Magnetic black sand may include magnetite with several other dense minerals. A magnet concentrates grains but does not identify every component.

Human use

Uses and significance

Magnetite is a major iron ore and is used in dense media, pigments, magnetic materials, and specialized industrial applications.

Safety and limits

Field notes

A magnetic rock is not automatically a meteorite.
Keep strong magnets away from electronics and medical devices.
Mine dumps and iron-rich dust can contain additional hazardous minerals.

This guide supports preliminary field identification, not a laboratory determination, appraisal, hazard assessment, or statement of ownership or collecting permission. Verify land status and local rules before handling or collecting material.

Source basis

Authoritative sources

LithoMap wrote this guide in original language using the scientific concepts and physical-property standards supported by these sources.

Minerals and their physical properties U.S. National Park Service
Mohs Hardness Scale U.S. National Park Service
Natural Gemstones: Mineral Gemstones U.S. Geological Survey

Editorial review: September 17, 2026.

Back to mineral identification