mineral
Magnetite (in matrix)
Magnetite (Fe3O4)
Hardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal structure: Isometric (octahedron); Cleavage: None; Specific Gravity: 5.17-5.18
- Hardness
- 5
- Color
- Black to dark gray
- Luster
- Metallic to submetallic
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Physical properties
Hardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal structure: Isometric (octahedron); Cleavage: None; Specific Gravity: 5.17-5.18
Formation & geological history
Formed in igneous or metamorphic rocks through crystallization of magma or hydrothermal activity. Often found in banded iron formations resulting from ancient oceanic sedimentation.
Uses & applications
Primary ore of iron; used in heavy media separation, as magnetic carrier in industrial processes, and sometimes as a minor gemstone or collector mineral.
Geological facts
It is the most magnetic naturally occurring mineral on Earth. Small grains are found in the brains of several animals to aid in navigation through magnetoreception.
Field identification & locations
Identifiable by its strong attraction to magnets. It often leaves a black streak. Commonly found in iron mines and beach sands (as black sands).
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Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock
![Biotite Schist (Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]) — metamorphic](https://media.rock.id/9ca564b5-bc87-402b-965a-69b21f9aa6bf-thumbnail.jpg)
Biotite Schist
Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]
metamorphic
![Green Apatite on Albite (Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]) — mineral](https://media.rockidentification.com/2391a63f-fb20-47d5-af9a-2035851eb32e-thumbnail.jpg)
Green Apatite on Albite
Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]
mineral