Sunday, January 9, 2005

Duncan Kwok, Peter Russell, and Amy Sittler

Talc mine, 1891
The mineral talc is a hydrous magnesium silicate. A massive talcose rock is known as steatite, and an impure massive variety is called soapstone. 

The name talc

The name talc is believed to be derived from the Arabic word talg or tolk meaning mica, since talc forms mica-like flames. The present name was given by Georgius Agricola in 1546. Kerite is a common name also used for talc.

Uses of talc

There are many uses of talc, especially as an industrial mineral because of its resistance to heat, acid and electricity. Because of these resistances it can be used as counter tops, electrical switchboards, ceramics, and insecticides. It is most commonly known as the main ingredient in talcum powder. It is also an important filler in paints and rubber. Talc is used commercially because it can retain fragrance, luster, purity, softness and whiteness. Some of the major markets for talc are ceramics, paint paper and plastics. Ground talc is used in roofing, and cosmetics.

Physical characteristics

Talc can be blue, pale green, gray, pink, white, yellowish or brownish white to almost silver. Its luster is dull to pearly or greasy. What determines these characteristics are its natural or artificial impurities. Talc only has a hardness of one on the Moh's scale of hardness. This translates into a very soft material, which results from its layered nature. Naturally, this substance is hydrophobic (dislikes water), and tends not to absorb water, therefore giving some of its favourable water-resistant characteristics.

Talc and pyrophyllite

Both of these minerals are nearly identical, each being very soft, talc is one on Moh's scale of hardness, and pyrophyllite is one to two. Both can be easily crushed and cut, because they are so soft. Also both have perfect cleavage in one direction, allowing these minerals to break into thin sheets. Each feels greasy to the touch, this is why talc is used for a lubricant, and both are formed in metamorphic environments.

Gillespie Talc Mine, Madoc, Ontario

Substitutes and alternative sources

Some replacements for talc when manufacturing ceramics are clays and pyrophyllite. Kaolin and mica can be substituted instead of talc in rubber paint and plastics production. For paper production, kaolin can be used in place of talc. There is an abundance of talc with sufficient amounts for many decades to come, but some of these alternatives may be cost-effective depending on the cost of talc. China is the worlds top producer of Talc followed by the U.S. and Japan. 

Canada talc mines

Talc was first discovered on a farm in Madoc in the 1880s. It was in 1896 that the Henderson Talc Mine came into production. In 1911 the Conley Mine opened in the adjacent property, where there contained a northeast extension of the Henderson ore body. The mines went through various owners until 1937, when the Henderson and Conley mines were merged into one under the name Canada Talc Limited. Again in 1951 Canada Talc was bought by Canada Talc Industries Limited. More than 800,000 tons of high-grade talc has been mined from this deposit, to date. 

To be continued in the next issue...