GO 336 Final Webpage Project

Corundum: Final Webpage Project

John Waechter


www.emporia.edu/earthsci/amber/go336/waechter/

The webpage was created for my mineralogy course at Emporia State University. A report over the mineral corundum, its varieties and uses is shown below.

Table of Contents

Introduction

The mineral corundum is one of the hardest known substances on the face of this earth. It only takes a back seat to diamond in the hardness category. This mineral also produces some beautiful gemstones that are known worldwide. Corundum varieties are called ruby and sapphire, which occur around the world. It has industrial uses too that help our society on an everyday basis.

Corundum Information

To start off with the definition of a mineral is, “an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes (www.webmineral.com/Mineral_Definition.shtml). The mineral corundum is composed of aluminum and oxygen. It has a chemical formula of Al2O3. The molecular weight of this mineral is 101.96 grams, 53% Al and 47% O. This mineral can be found in areas where there has been some form of contact metamorphism taking place. It has a density of about 4.0 and a hardness of 9 on the Mohs hardness scale. This mineral has a vitreous luster and can be found in colors of blue, red, yellow, brown, and gray along with being colorless (http://webmineral.com/data/Corundum.shtml .)

The name of this mineral is derived from Sanskrit, kuruvinda which stands for “ruby.” It belongs to the trigonal or hexagonal crystal system. The Webmineral.com website (webmineral.com/crystal/Trigonal-HexagonalScalenohedral.shtml) referred to the crystal class as hexagonal scalenohedral or Bar3 2/m. It can occur in hexagonal prism or hexagonal scalenohedral crystal forms and may display a tabular habit (www.mindat.org/min-1136.html.)

Corundum can be used as an abrasive, such as on grinding wheels as paper and belt abrasives because of its high hardness and tenacity or ability to resist breaking down. The mineral can also be used in machines as emery cloth. Industrial quality corundum is be mined in Zimbabwe, Russia, and India. This mineral can also be found on the Greek island of Naxos. Corundum can usually occur with or around other minerals like garnet, ziricon, rutile, tourmaline, topaz, and calcite.

The image up and to the right of corundum displays the hexagonal prism and pinacoid termination. It was taken from Mindat.org, http://www.mindat.org/min-1136.html.

Varieties of Corundum

The mineral species corundum is divided into two variety names based on color. The red variety of corundum that is colored by minute amounts of chromium is called ruby. Any other color of corundum in gem quality is called sapphire and except for blue, is prefaced with the color. For example, there is purple sapphire, green sapphire, yellow sapphire, orange sapphire, etc. but if sapphire is used alone it refers to some shade or blue. For more details, read on.

Ruby: this is one of the varieties of corundum. It is used as a gemstone and can be found in many places such as Montana in the U.S. Ruby is considered the birthstone for the month of July and is usually a purplish or blue red or orangey red color, which results from the element chromium acting as an impurity to create the red color. It is valued when a transparent crystal is found that is large enough to fashion into jewelry. However, to enhance the color and remove imperfections much of the corundum used in jewelry has been heat-treated to improve the quality of color and clarity. Since Ruby is hard and tough, it is durable for jewelery and considered valuable. According to the International Gem Society Reference Library (www.gemsociety.org/info/info.htm), which has additional information on ruby online, the cleaner stones do not require any special kind of precautions of techniques in order to keep them in their original form ((http://www.gemsociety.org/info/gems/Ruby.htm.)

Image up and left is a ruby crystal in a natural form. The image was taken from Mineral Miners, http://www.mineralminers.com/html/rbymins.stm.

Sapphire is another form of corundum and associated most often with this blue color seen in the image. Sapphire most of the time appears with a blue color but can also be yellow, pink, orange, and purple. The sapphire has 9 hardness, next to diamond at 10 on Mohs Hardness Scale, and this allows the gemstone to be popular for jewelry purposes. Like ruby, there really is no special requirement in order to take care of the stone and to make sure that it stays in its origianl form. Sapphire is formed from pure aluminum oxide with a few iron inclusions in order to give it the blue color. Sapphires can be found in India, Burma, Ceylon, Thailand, Vietnam, Austrailia, and Brazil (www.gemstone.org/gem-by-gem/english/sapphire.html.)

Faceted sapphire shown up and right is from Gemstone.org, http://www.gemstone.org/gem-by-gem/english/sapphire.html.

Conclusions


It is easy to see how this mineral is very versatile. It can be used as an abrasive in industry and as a gemstone in order to make something beautiful. This mineral is sought after because of its hardness and its gem quality and importance. Corundum has been important in history and will continue to be valued in today's society because of its utility and beauty.

Sources

"Corundum." Mindat.Org. 15 Nov. 2007 http://www.mindat.org/min-1136.html.

"Corundum Mineral Data." Web Mineral. 11 Nov. 2007 http://webmineral.com/data/Corundum.shtml.

"Mineral Definitions." Mineral Definitions. 10 Nov. 2007 http://www.webmineral.com/Mineral_Definition.shtml.

"Ruby: July's Birthstone." Rubies, Ruby Information. 11 Nov. 2007 http://www.gemsociety.org/info/gems/Ruby.htm.

Schumann, Walter. Minerals of the World. New York: Sterling Co,. Inc., 1992. 120.

For more information email kingrooster48@yahoo.com.

Related Links
Emporia State University
www.emporia.edu 		Earth Science at ESU
www.emporia.edu/earthsci
Mineralogy Webpage Assignment
http://www.emporia.edu/earthsci/amber/
go336/assign.htm 		Past Student Projects
www.emporia.edu/earthsci/amber/
go336/webpages.htm