Serpentine is green and sometimes white, and occurs only in metamorphic rocks.
There are three main serpentine minerals:
All are generally green from a significant iron content replacing the magnesium; other metals may include Al, Mn, Ni and Zn, and silicon may be partly replaced by Fe and Al.
Serpentine rock is subjected to high pressures and fairly low temperatures.
The coastal region of northern California is largely made of serpentinite.
White serpentine asbestos has been used in virtually every product from wall insulation and pipe lagging to automotive brake linings and fire suits. Recent legislation in the U.S. was introduced to ban new uses of asbestos in 2007 and phase out asbestos completely by 2016; however, there are still some 3500 asbestos-containing products on the market. In addition, the Canadian, Russian and Chinese asbestos industries continue to produce hundreds of thousands of tons every year, most of which is exported to developing countries.
Properties of serpentine asbestos :
Chemical formula : (Mg)2–3(Si)2O5(OH)4,
Color : White, yellow, green, gray, brown, black, purple; sometimes multicolored, especially green and yellow.
Crystal System : Monoclinic
Transparency :Translucent to opaque. Rarely transparent.
Luster: Greasy, waxy, or silky
Tenacity :Brittle. Fibrous Serpentine is flexible and elastic.
Article publié pour la première fois le 24/10/2013None found.