mineral
Magnetite
Magnetite (Fe3O4)
Color: Iron-black to dark gray; Luster: Metallic to submetallic; Hardness: 5.5 - 6.5; Special property: Strong magnetism; Crystal structure: Isometric/Octahedral; Specific Gravity: 5.1 - 5.2
- Hardness
- 5
- Color
- Iron-black to dark gray
- Luster
- Metallic to submetallic
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Physical properties
Color: Iron-black to dark gray; Luster: Metallic to submetallic; Hardness: 5.5 - 6.5; Special property: Strong magnetism; Crystal structure: Isometric/Octahedral; Specific Gravity: 5.1 - 5.2
Formation & geological history
Formed in igneous, metamorphic, and sedimentary environments. Often found as an accessory mineral in igneous rocks like basalt and granite, or as massive beds in metamorphic banded iron formations.
Uses & applications
The most important ore of iron. Used in industrial processes as a heavy medium for coal washing, as a pigment (mars black), and historically for early compasses (lodestones).
Geological facts
Magnetite is the most magnetic of all the naturally-occurring minerals on Earth. Pieces of magnetite that act as natural magnets are called lodestones and were used by Vikings for navigation.
Field identification & locations
The easiest field identification is its strong attraction to a magnet. It has a black streak. Found globally, specifically in huge deposits in Kiruna, Sweden, and the Lake Superior region of North America.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic