EPA 2014c), was the site of a former mine that produced vermiculite contaminated with a mixture of asbestiform amphiboles, including winchite, richterite, and tremolite asbestos (Meeker et al.
magnesio-riebeckite, magnesio-arfvedsonite, winchite, richterite, fluoro-edenite, antigorite, and erionite) are known to be associated with ARD among exposed populations, and health investigations are urgently needed for populations exposed to these mineral fibers.
However, at T > 950[degrees]C instead of layered hectorite a needle-like richterite
The hornblende-plagioclase thermometry actually consist of two reactions, the A thermometer uses the edenite-tremolite reaction (edenite + 4 quartz = tremolite + albite, in quartz rich rocks) and the B thermometer uses the edenita-richterite
reaction (edenite + albite = richterite
+ anorthite) (Holland and Blundy, 1994).
Amphibole forms of asbestos are often divided into those with considerable commercial exploitation (amosite and crocidolite) and those that are encountered largely as intrusions into other mineral deposits (tremolite, actinolite, anthophyllite); thus, tremolite is found in many chrysotile ore beds, and an amphibole that has been variously labeled as tremolite, richterite
, or winchite is found in vermiculite ore from Libby, Montana.
In contrast, Libby amphibole is a mixture of six amphiboles, mostly winchite (84%), richterite
(11%), and tremolite (6%), including prismatic crystals, acicular fragments, and bundles of fibrils approximately 100 nm to 1 [micro]m in diameter with lengths up to 20 [micro]m (Meeker et al.
Libby amphibole asbestos was determined to be composed of tremolite, winchite, and richterite
(Meeker et al.
KEY WORDS: amphibole fibers, asbestos, asbestosis, asbestos-related disease, insulation, lung cancer, mesothelioma, richterite, tremolite, winchite.
Geological Survey has characterized the respirable fraction of asbestiform amphiboles contaminating the Libby vermiculite as approximately 84% winchite, 11% richterite, and 6% tremolite (Meeker et al.
There has been no published human or animal (and very little in vitro) research on the potential health effects of winchite and richterite (Cleveland 1984; Collan et al.