mineral
Magnetite or Hematite (Iron Stone)
Magnetite (Fe3O4) or Hematite (Fe2O3)
Hardness: 5.5-6.5; Color: Black, dark gray, or brownish-red; Luster: Sub-metallic to dull; Crystal Structure: Isometric or Hexagonal; Streak: Black (Magnetite) or Red/Cherry-red (Hematite).
- Hardness
- 5
- Color
- Black, dark gray, or brownish-red
- Luster
- Sub-metallic to dull
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Physical properties
Hardness: 5.5-6.5; Color: Black, dark gray, or brownish-red; Luster: Sub-metallic to dull; Crystal Structure: Isometric or Hexagonal; Streak: Black (Magnetite) or Red/Cherry-red (Hematite).
Formation & geological history
Commonly forms in igneous and metamorphic rocks through hydrothermal processes, or in sedimentary environments as banded iron formations (BIFs). Many were formed over 2 billion years ago during the Great Oxygenation Event.
Uses & applications
Primary ore of iron used for steel production; also used as a heavy media for coal washing, in pigments, and as a polishing agent (jeweler's rouge).
Geological facts
Magnetite is the most magnetic naturally occurring mineral on Earth. Lodestones are naturally magnetized pieces of magnetite used by ancient civilizations for early navigation compasses.
Field identification & locations
Identify using a magnet or a streak test. Magnetite will be strongly attracted to a magnet, while Hematite will leave a reddish-brown streak on unglazed porcelain. Commonly found in lake beds, mountain ranges, and beach sands as 'black sand'.
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