Haematite
Antiferromagnetic
mineral, but due to slightly imperfect antiparallelism of the magnetic
moments it exhibits a weak ferromagnetic
moment. Common in oxidised
volcanic rocks and in sediments formed in an oxidising environment. It
is the final product of prolonged oxidation of magnetite or maghaemite.
It is also formed by dehydration of goethite. May also from a solution by
precipitation in certain sediments (red sediments) and in hydrothermal
veins. Very common in tropical and subtropical soils. The name is
derived from the Greek word aima, meaning blood. Mentioned by the Roman
poet Vergilius in the 1st century BC in the Eneid. Also called oligist from the
Greek work oligos, meaning very few, because it contains a lower
percentage of iron compared to magnetite. Colour: steel gray to black.
In powder form it has a red cherry or blood colour to reddish brown.
Metallic reflectance. Hardness between 5 and 6.5. It occurs in massive
forms as drused, botryoused or as fibrous concretions or also as an
aggregate of laminar crystals or in rose like form. Occurs also as
hexagonal platelets, but in general isometric and of irregular form.
Iron ore. Utilised as a precious stone, or colourant, abrasive and as a
polishing product.
Hellenistic Period
Cultural period in Greece (336-146 BC) between the conquest of the
Persian Empire by Alexander the Great and the establishment of Roman
supremacy.