Cottage Q&A
QUESTIONWhen I was a child, I was fascinated by the mica deposits around our cottage on the Big Rideau. We also had a woodstove in our kitchen with a small front window I was told was made of mica. Does mica have any other uses?
ANSWER
"My family had a stove like that too," says Mike Cosec, district geologist for Ontario's Ministry of Northern Development and Mines in Sudbury, Ont., "and yes, those windows were mica." The word actually refers to a group of silicate minerals whose crystal structure typically forms large sheets, which split easily into very thin transparent or translucent layers. These have remarkably high heat resistance, hence their historic use as windows in woodstoves and as insulation in electrical connectors and transformers.
There are mica fields in many parts of Ontario cottage country, notably the regions around Mattawa, Bancroft, North Bay, and Sudbury, and these were extensively mined in the first half of the 20th century. Because the material shatters so easily, however, mica mining required labour-intensive work, mostly by hand rather than by machine. When synthetic alternatives to mica were developed, during and after WW II, most of the mines closed down.
Scrap mica is still collected from old quarries and mine sites. Ground fine, it offers heat resistance to lubricants for high-speed equipment such as oil well drills. It's also used in high-gloss paints - particularly auto paints, where it imparts extra durability as well as that much-prized metallic lustre.
* Published in the June 2004 issue of Cottage Life
