HAEMATITE or HEMATITE, a mineral consisting of ferric oxide (corresponding to 7o% of iron). The name is derived from the Gr. aiµa, "blood," in allusion to its typical colour, whence the mineral is also called red iron-ore. When crystallized it is often black; but the powdered mineral shows the characteristic red colour. It crystallizes in the hexagonal system with rhombohedral symmetry. Cleavage, imperfect. Hardness, 6. Sp.g., 5.2. Lustre, metallic. Nearly opaque. The brilliant lustre of the steel grey crystallized variety, often in tabular form, has given it such names as specular iron-ore, looking-glass ore, iron glance. When in very thin scales and plates it is known as mica ceous iron-ore. Scales of specular ore occur on the surface of lavas in volcanic districts. This is no doubt a sublimation product formed by the inter-action of steam and ferric chloride. Haema tite is often compact or massive with a mammillated surface and an internal fibrous structure (pencil-ore). A reniform variety is known as kidney-ore. Much haematite occurs in an earthy form, when it is termed soft red ore. Red ochre or reddle is an earthy variety used for the preparation of the pigment having the same name. Rouge is another preparation made from haematite. On account of its high iron content and freedom from phosphorus, haematite constitutes a valuable iron-ore. (F. H. HA.)