Hematite

Chemical Formula : Fe₂O₃
Hardness : 5-6
Cleavage : None but parting present in twins
Luster : Metallic to sub-metallic to dull
Color : Dull to bright red when earthy and compact, or steel gray when crystalline or specularite.
Streak : Red-brown
Density : 5.26
Diagnostic Features and Trivia : Hematite mean blood like due to its red streak. It was so named because when ground the water on the grindstone would soon resemble blood as it carried the powdered hematite away.
Crystal System and Habit : Hexagonal; uncommon crystals are thick to thin tabular on {0001}
Twinning : {0001} penetrating and {01-12} as lamellar
Polymorphs : None
Index of Refraction : omega=3.15-3.22; epsilon=2.87-2.94