Hematite - Fe2O3

The name hematite is derived from the Greek word for blood aima (blood-red stone) because hematite can be red.

Hematite consist of oxygen ions in hexagonal closet packing, with Fe3+ io two-third of the interlayer, octahedral sites. Hematite structure is similar to the corundum structure. Hematite is relatively pure Fe2O3 with only minor Fe2+, Ti, Al and Mn; solid solution is very limited between Hematite and magnetite (Fe3O4), Ilmenite (FeTiO3) and corundum (AL2O3). Hematite and ilmenite form a complete solid solution at temperatures above 950°C.

Hematite has several varieties, each with their own unique names:

• Hematite Rose is a circular arrangment of bladed crystals giving the appearance of the flower of a rose.
• Tiger Iron or BIF (banded Iron Formation) is a sedimentary deposit of approximately 2.2 billion years old that consists of alternating layers of silver gray hematite and red jasper, chert or even tiger eye quartz.
• Kidney Ore is the massive botryoidal form and gives the appearance of lumpy kidney-like masses.
• Oolitic Hematite is a sedimentary formation that has a reddish brown color and an earthy luster and is composed of small rounded grains.
• Specularite is a micaceous or flaky stone that is sparkling silver gray and sometimes used as an ornamental stone.

Optical Properties:
• Color: Hematite is usually opaque, but can be deep-red brown
• Interference colors: Interference colors are very high but masked by red-brown colors


Bibliography



• Deer, W.A., Howie, R.A., Zussman, J. (1998) Rock-forming Minerals.
• Optical Mineralogy : The Nonopaque Minerals by Phillips / Griffen
• E. WM. Heinrich (1956): Microscopic Petrografy. Mcgraw-hill book company,inc
• Nesse, William D., 1986, Introduction to Optical Mineralogy: New York, Oxford University Press

Photo
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Hematite concretions in a Basalt from Vulsini Volcanic Complex. PPL image , 10x (Field of view = 2mm)
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Hematite concretions in a Basalt from Vulsini Volcanic Complex. PPL image , 10x (Field of view = 2mm)
eematiter(3).jpg

Hematite concretions in a Basalt from Vulsini Volcanic Complex. PPL image , 10x (Field of view = 2mm)
ematite.jpg

Hematite concretions in a Basalt from Vulsini Volcanic Complex. PPL image , 10x (Field of view = 2mm)
ematite(2).jpg

Hematite concretions in a Basalt from Vulsini Volcanic Complex. PPL image , 10x (Field of view = 2mm)
ematite(3).jpg

Hematite concretions in a Basalt from Vulsini Volcanic Complex. PPL image , 10x (Field of view = 2mm)