Hematite is an important iron oxide mineral (Fe₂O₃) and one of the primary sources of iron worldwide. Here’s a detailed overview:
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Key Properties of Hematite:
– Chemical Formula: Fe₂O₃ (Iron(III) oxide)
– Crystal System: Trigonal (hexagonal)
– Color: Metallic gray to black (crystalline), reddish-brown (earthy forms)
– Streak: Reddish-brown (diagnostic feature, even in metallic specimens)
– Luster: Metallic to dull (depending on form)
– Hardness: 5.5–6.5 on the Mohs scale
– Density: 5.0–5.3 g/cm³ (relatively heavy for a mineral)
– Magnetism: Weakly magnetic after heating (unlike magnetite, which is strongly magnetic).
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Forms & Varieties:
1. Specular Hematite: Shiny, metallic-gray crystals with a mirror-like luster.
2. Botryoidal Hematite: Globular, bubbly formations (“kidney ore”).
3. Oolitic Hematite: Composed of tiny spherical grains.
4. Earthy Hematite (Red Ochre): Soft, red powdery form used as a pigment.
Geological Occurrence:
– Forms in sedimentary, metamorphic, and igneous environments.
– Common in banded iron formations (BIFs), hydrothermal veins, and as a weathering product of iron-bearing minerals.
– Major deposits: Brazil, Australia (Hamersley Basin), China, India, and the USA (Lake Superior region).
Uses of Hematite:
1. Iron Ore: Primary source for steel production (~70% Fe content when pure).
2. Pigment: Red ochre has been used since prehistoric times in art and cosmetics.
3. Jewelry & Ornamentation: Polished into beads or carvings (“black diamond” effect).
4. Radiation Shielding: Due to its high density, it’s sometimes used in shielding materials.
Fun Facts:
– The name comes from the Greek *haima* (“blood”), due to its red streak.
– Mars’ reddish appearance is caused by hematite-rich dust on its surface (“Planet Mars”).
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