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
• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.
.jpg) Hematite concretions in a basalt from Vulsini Volcanic Complex, Italy. PPL image , 10x (Field of view = 2mm) |
.jpg) Hematite concretions in a basalt from Vulsini Volcanic Complex, Italy. PPL image , 10x (Field of view = 2mm) |
.jpg) Hematite concretions in a basalt from Vulsini Volcanic Complex, Italy. PPL image , 10x (Field of view = 2mm) |
 Hematite concretions in a basalt from Vulsini Volcanic Complex, Italy. PPL image , 10x (Field of view = 2mm) |
.jpg) Hematite concretions in a basalt from Vulsini Volcanic Complex, Italy. PPL image , 10x (Field of view = 2mm) |
.jpg) Hematite concretions in a basalt from Vulsini Volcanic Complex, Italy. PPL image , 10x (Field of view = 2mm) |