Magnetite

Magnetite single crystals, showing octahedral habit.

Magnetite crystals covering the surface of a rock.

The (cubic) crystal structure of magnetite, CrystalMaker.

Magnetite is the most abundant oxide in igneous rock.

Fe₃O₄

Non-silicate

Crystal system: cubic

Colour in hand specimen: black
Streak: black
Cleavage: none
Hardness: 7.5-8

Colour in plane polarised light: almost opaque
Relief: high
Isotropic

M501 Magnetite
Brazil
Crystals showing the characteristic octahedral form
Silver-black colour
Metallic lustre

M502 Magnetite
Hay Tor, Devon
A mass of small octahedral crystals embedded in a metamorphic rock
Silver-black
Metallic lustre
No cleavage

magnetite
iron oxide
opaques