mineral

Magnetite (potentially as a Lodestone or within Ironstone)

Magnetite (Fe3O4)

AI-generated identification · may be incorrect

Hardness: 5.5-6.5 on Mohs scale; Color: Black, iron-gray; Luster: Metallic to submetallic; Crystal Structure: Isometric (often octahedral, but frequently massive or rounded as a pebble); Cleavage: None; Specific Gravity: 5.1-5.2 (very heavy for its size)

Hardness: 5
Color: Black, iron-gray
Luster: Metallic to submetallic

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Usually forms in igneous rocks like basalt or gabbro, or in metamorphic rocks as a result of regional metamorphism. This specific specimen appears to be a stream-tumbled or water-worn pebble, potentially originating from a Precambrian or Paleozoic formation and weathered out of the parent rock.

Uses & applications

Primary ore of iron; used in heavy media separation, as a pigment (mars black), in magnetic clutches, and as a collector specimen due to its natural magnetism.

Geological facts

Magnetite is the most magnetic mineral on Earth. When it is naturally magnetized and acts as a magnet itself, it is known as Lodestone. Ancient mariners used Lodestone as the first primitive compasses to navigate the seas.

Field identification & locations

Identify in the field by its high density (feels heavy), black streak on a porcelain plate, and strong attraction to a magnet. Look for it in heavy sand deposits or near volcanic outcrops. It is often found in riverbeds as dark, heavy pebbles.