Tremolite

Tremolite is a comparatively rare type of asbestos that was used far less in manufacturing than other type of asbestos.  Pure tremolite is a creamy white color, but frequently it contains iron, which makes the crystal look green.  Unlike chrysotile, which is the only serpentine asbestos, tremolite is an amphibole asbestos like amosite, crocidolite, anthophyllite, and actinolite.  Instead of curly fibers, it has long, thin crystalline fibers and is more brittle than chrysotile.  Tremolite exists in underground rock formations, remaining undisturbed until it is mined.

Tremolite is very dangerous for exposed workers and individuals. People who come in contact with tremolite fibers are at risk of developing asbestosis, lung cancer, and mesothelioma.

Dangerous instances involving tremolite

When people in Fairfax County, Virginia became aware that the ground under their county contained large quantities of tremolite, the county government took precautions.  The county required construction site monitoring of air quality and soil, and it ordered newly developed real estate areas to lay six inches of clean material over the ground surface.

However, the largest U.S. scare to date involving tremolite occurred in Libby, Montana.  Libby, Montana was a mining town where a vermiculite (trade name Zonolite) mining company operated.  Vermiculate is a mica ore extracted from the ground that has heat-expansion properties and is used for sound insulation, fireproofing, and plant growth.  The vermiculite extracted from the Libby mine also contained tremolite dust contaminants, which when mined had devastating effects on the health of Libby residents.  Over several decades, several hundred miners in Libby, Montana died from tremolite exposure.