mineral
Botryoidal Hematite (Kidney Ore)
Iron(III) oxide (Fe2O3)
Hardness: 5.5-6.5 on Mohs scale; Color: Steel-gray to black with reddish undertones; Luster: Metallic to sub-metallic; Crystal structure: Trigonal; Gravity: 5.26
- Hardness
- 5
- Color
- Steel-gray to black with reddish undertones
- Luster
- Metallic to sub-metallic
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Physical properties
Hardness: 5.5-6.5 on Mohs scale; Color: Steel-gray to black with reddish undertones; Luster: Metallic to sub-metallic; Crystal structure: Trigonal; Gravity: 5.26
Formation & geological history
Formed in hydrothermal veins and as a result of the oxidation of iron-rich minerals. The botryoidal (grape-like) texture occurs as crystals grow outward from multiple centers in a confined space.
Uses & applications
Primary ore of iron; also used in jewelry, as a polishing abrasive (jeweler's rouge), and in some pigments.
Geological facts
The name comes from the Greek word 'haima', meaning blood, because the mineral turns blood-red when powdered. This specific form is often called 'Kidney Ore' due to its rounded shape.
Field identification & locations
Identify by its high density/weight for its size and its distinctive reddish-brown streak when rubbed against an unglazed porcelain plate. Commonly found in Cumbria (UK), Morocco, and the Great Lakes region of the USA.
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Other mineral specimens
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
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock