At Sado field, hornblende in form of riebeckite
occurs as minor phase and the source is the host lithology (metagabbro) .
[section] 61.141, states: "Asbestos means the asbestiform varieties of serpentinite (chrysotile), riebeckite
(crocidolite), cummingtonite-grunerite, anthophyllite, and actinolite-tremolite." Other federal agencies have adopted similar definitions of asbestos that include the same six forms of asbestos, including 29 C.F.R.
The principal rock of the Warsak igneous complex is a medium-grained, gneissic alkaline granite (Kempe, 1973) composed of microcline with minor albite, quartz, aegirine, riebeckite
If it replaces a mineral called riebeckite
, it forms a semiprecious gemstone called tiger's eye.
For regulatory purposes they are defined as the asbestiform varieties of chrysotile (serpentine), crocidolite (riebeckite
), Amosite (cummingtonite-grunerite), anthophyllite, tremolite and actinolite.
The amphibole is greenish to brownish to blue, and in some rocks looks like typical riebeckite
. The clinopyroxene is greenish pleochroic, and may range from aegirine augite to aegirine.
Numerous experimental animal studies have demonstrated the carcinogenicity of fibers of the six commercially used asbestos minerals [the serpentine chrysotile and the amphiboles cumming-tonite-grunerite asbestos (amosite), tremolite asbestos, riebeckite
asbestos (crocidolite), actinolite asbestos, and anthophyliite asbestos in multiple species (rats, hamsters, mice) by exposure via inhalation, intrapleural injection, implantation, and ingestion (reviewed by Kamp 2009; Lippmann 1990).
Arfvedsonite prevails while riebeckite
(Fediuk, 2005), for which most manuals on systematic mineralogy claim Socotra for the locus typicus, is substantially less frequent and mostly restricted to narrow rims of zoned amphibole columns only.
Associated minerals are: riebeckite
, analcime, sodalite and steenstrupine-(Ce).
The minerals include K-feldspar (microcline), quartz, plagioclase, biotite, aegirine-augite, hornblende, riebeckite
, titanite, epidote, apatite, zircon and magnetite.
These include microscopic black crystals of ilvaite associated with prehnite or datolite, and fibrous blue coatings of riebeckite
on basalt surfaces (Bradley Platkin, personal communication).