Hematite is a heavy and relatively hard ferric oxide mineral, which crystallizes in a rhombohedral system. The mineral has derived its name from the Greek word for blood, as it often observed in red powdered form. Hematite has the same crystal structure as that of corundum and ilmenite.
Large deposits of hematite occur in banded iron formations. Gray hematite is found in places with mineral hot springs or standing water, such as the one in Yellowstone National Park, North America.
Hematite can also occur as a result of volcanic activity. Clay-sized hematite crystals occur as a secondary mineral along with oxyhydroxides, such as goethite, or other iron oxides as a result of the weathering process in soil.
The most common deposits of hematite are sedimentary deposits, such as the Lake Superior district in North America. Other important deposits include Quebec and Labrador in Canada, Minas Gerais in Brazil, and Cerro Bolívar in Venezuela.
Properties of Hematite
Hematite occurs in different forms and has separate names. The coarse-grained crystals of hematite, with a steel-gray color and metallic luster, are known as specular iron ore. Thin scaly ores are known as micaceous hematite. Ruddle or red ochre refers to soft, fine-grained, earthy crystals.
Hematite is paramagnetic in nature, and has an opaque transparency and uneven fractures. The mineral is harder than pure iron, but very brittle. Hematite, along with ilmenite, forms a complete solid solution at temperatures above 950°C.
Hematite finds application in the following:
- Ornamental jewelry making
- Manufacture of nails, bolts, and steel tools
- Construction of bridges