Magnetite with Pyrite or Chalcopyrite inclusions

Physical Properties

Hardness: 5.5-6.5 (Magnetite); Color: Iron-black to dark grey with golden/brassy metallic flecks; Luster: Metallic to sub-metallic; Crystal Structure: Isometric (octahedral); Cleavage: None (parting); Specific Gravity: 5.17-5.18.

Formation & Geological History

Typically forms in igneous rocks like basalt or diabase, or in metamorphic rocks and banded iron formations. It can also form in hydrothermal veins where metallic sulfides like pyrite precipitate alongside iron oxides.

Uses & Applications

Primary ore of iron; used in heavy media separation, as a pigment (ochre), and in magnetic recording media. Brassy inclusions make specimens popular for amateur mineral collectors.

Geological Facts

Magnetite is the most magnetic naturally occurring mineral on Earth. When it is naturally magnetized, it is called lodestone and was used in the first compasses.

Field Identification & Locations

Identify in the field using a strong magnet (it will be highly attracted) and checking for a black streak on a porcelain plate. Look for brassy, glittery inclusions that don't wash off.

Identified on: 4/27/2026

Mode: Standard