Magnetite
Mineral Fe3O4
About it
Black octahedrons and grains that leap to a magnet, with a black streak; naturally magnetized pieces are lodestone. Common in black sand; sharp crystals come from Cerro Huañaquino, Bolivia, and the Swiss Alps.
- Type
- Mineral
- Group
- Oxide, spinel group
- Formula
- Fe3O4
- Hardness (Mohs)
- 5.5–6.5
- Specific gravity
- 5.17–5.18
- Streak
- black
- Lustre
- metallic, submetallic
- Crystal system
- Isometric (cubic)
- Colours
- black, grey
- Transparency
- opaque
- Cleavage and fracture
- none; octahedral parting, uneven to subconchoidal fracture
- Magnetic
- Strongly
Typical values: real specimens vary. For more, see mindat.org.