Hematite

by John Inmon

This webpage project was created for a mineralogy course in November 2003 at Emporia State University. The main focus of this page is the negative aspects of hematite, however there are also several positive attributes. A wonderful page on these useful qualities of hematite can be found on my colleague's web page, Hematite's Positive Aspects.

Introduction to Hematite
What is hematite?
Abuses
Uses
Sources

Introduction to Hematite

Throughout the centuries, mankind has searched for useful materials and methods to improve the quality of life. From the first fires sparked by lightning to the advent of electricity, humanity's knowledge base has swelled. Things that can be a blight often have a useful purpose, and what is intended to benefit us also can also have unintended consequences. Hematite is a good example of this paradox.

What is hematite?

Hematite (Fe2O3) is a reddish brown to black mineral with a metallic luster while in crystal form and a dull luster in earthy varieties (Klein, 2002, p. 381). Klein described hematite's occurrence in contact metamorphic deposits and as an accessory mineral in feldspathic igneous rocks (p. 381). It is a common mineral that is found in rock of all ages. In the United States, enormous bedded deposits yield an earthy variety that furnishes a large portion of the world's iron ore (p. 381). These deposits are mainly located around the shores of Lake Superior in Michigan, Wisconsin, and Minnesota (p. 381). While the United States still has a considerable production of iron ore from hematite, the rich deposits have been considerably depleted. In the future lower grade deposits will have to be used. Notable deposits have also been found in Venezuela, Brazil, Canada, and Australia (p. 382).


Metalic Hematite
Image taken from http://www.minerals.net/mineral/
oxides/hematite/hematit1.htm,
from Hershel Friedman's collection, http://www.minerals.net/mineral/oxides/
hematite/hematite.htm#Picture. 		According to Klein (2002) hematite's crystallographic and physical properties are:

1. Hexagonal crystal system

2. 5 ½-6 ½ hardness

3. Reddish brown to black color

4. Red streak

5. Specific gravity 5.26

6. Metallic luster in crystals

7. Dull luster in earthy varieties


Earthy Hematite
Image taken from http://www.minerals.net/mineral/
oxides/hematite/hematit6.htm,
from Hershel Friedman's collection,
http://www.minerals.net/mineral/
oxides/hematite/
hematite.htm#Picture

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Abuses

The extraction of hematite has several hazards associated with it, both to people and the environment. Water used in the extraction process and that collected after the mine was abandoned often have iron and aluminum sulfates present. This gives the water a very acidic ph (4.5) The altering of the ph and the introduction of larger quantities of iron and aluminum sulfate degrades the water quality killing off native plants and animal species (source 4). Also, sediments from the mine often clog streams causing flooding. In abandoned open pit mines, it is not uncommon for water to collect in the pit. The walls of these pits erode to the point of collapse (source 4). This can also cause a flooding hazard, much like the failure of a dam.

The tailings of the mine can cause a landslide. Another hazard associated with mining is the collapse of an underground mine. This can trap people inside or lead to sinkhole, troughs, tension cracks, or shearing (source 4). These disturbances of the ground can cause havoc with any building project in the area of the mine. Abandoned mines form a fire hazard because flammable gasses can build up underground (source 4). Underground hematite miners have a higher incidence of lung cancer when radon is present, than do surface hematite miners; and while hematite may not be declared a carcinogen, often times radon increases the chance of lung cancer due to poor ventilation (source 5).

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Uses
In 2002, hematite was the source of 90% of the iron mined in this country. Iron has more uses than can be counted and is essential to any industrialized society. It is a vital component of steel. In the past, hematite was used as a red or brown pigment. (source 2). Today it is not used as often because of the introduction of cheaper alternatives. This mineral can also be cut and polished to yield a relatively inexpensive gemstone. Hematite is made into bracelets, necklace, rings and ornamental figures.
Hematite has even been detected on Mars. In 1998 the Mars Global Surveyor (MGS) spacecraft found a large deposit of hematite near the equator of Mars. "We believe that the gray hematite is very strong evidence that water was once present in that area," said Victoria Hamilton, a planetary geologist at Arizona State University (ASU) (source 3.). She went on to say,
We think the deposit is fairly old. It was buried, perhaps, for several hundred million years or more and now it's being exposed by wind erosion. Water is essential to life as we know it and this finding bolsters the theory that life may have existed on Mars (source 3).

Polished hematite gemstone.
Image taken from The Gem Hut at,
http://www.gemhut.com/hematite.htm
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Sources

Source 1. Klein, C. 2002. Mineral science (22nd ed.). John Wiley & Sons Inc., NY.

Source 2. Friedman, H. 1997-2001. Hematite. World Wide Web URL: http://www.minerals.net/mineral/oxides/hematite/hematite.htm, from The Mineral and Gemstone Kingdom at http://www.minerals.net. Retrieved on November 25th, 2003.

Source 3. Barry, P. L. & Phillips, T. 2001. The lure of hematite. World Wide Web URL: http://science.nasa.gov/headlines/y2001/ast28mar_1.htm. Retrieved on November 25th, 2003.

Source 4. National association of abandoned mine land program, hazards, World Wide Web URL: http://www.onenet.net/~naamlp/hazards.htm, found within http://www.onenet.net/~naamlp/index.html. Retrieved on November 2nd, 2003.

Source 5. Haematite and ferric oxide: Ferric oxide (group 3) haematite (group 3) underground haematite mining with exposure to radon. 1987. International Agency for Research on Cancer (IARC) - Summaries & Evaluations, World Wide Web URL: http://www.inchem.org/documents/iarc/suppl7/haematite.html. Retrieved on November 2nd, 2003.

Source 6. Hematite, World Wide Web URL: http://www.gemhut.com/hematite.htm, within http://www.gemhut.com, Gem Hut. Retrieved on November 25th, 2003.

Created December 6, 2003; last update December 8, 2003. Return to GO 336 Student WebPages.