Chrysotile

Chrysotile
General
CategoryPhyllosilicates
Kaolinite-serpentine group
Formula
(repeating unit)
Mg3(Si2O5)(OH)4
(ideal)
IMA symbolCtl[1]
Strunz classification9.ED.15
Crystal systemMonoclinic: clinochrysotile (most common)
Orthorhombic: orthochrysotile and parachrysotile (both rare)
Crystal classClinochrysotile: prismatic (2/m)
Orthochrysotile and parachrysotile: pyramidal (mm2)
Space groupClinochrysotile: C2/m
Orthochrysotile and parachrysotile: Ccm21
Identification
Formula mass277.11 g/mol (ideal)
ColourWhite to greyish green
Crystal habitAcicular
FractureFibrous
Mohs scale hardness2.5–3
LustreSilky
StreakWhite
DiaphaneityTranslucent
Density2.53 g/ml
Optical propertiesBiaxial (+)
Refractive indexnα = 1.569, nγ = 1.570
Birefringence0.001 (max)
DispersionRelatively weak
Extinctionparallel
Melting point600–850 °C (1,112–1,562 °F) (decomposes)
Fusibilitydehydrates at 550–750 °C (1,022–1,382 °F)
Diagnostic featuresWhite to grayish green thin, flexible curved fiber
SolubilityInsoluble in water
Fibres degrade in dilute acid
References[2][3][4]

Chrysotile or white asbestos is the most commonly encountered form of asbestos,[5] accounting for approximately 95% of the asbestos in the United States[6] and a similar proportion in other countries.[7] It is a soft, fibrous silicate mineral in the serpentine subgroup of phyllosilicates; as such, it is distinct from other asbestiform minerals in the amphibole group. Its idealized chemical formula is Mg3(Si2O5)(OH)4.[5] The material has physical properties which make it desirable for inclusion in building materials, but poses serious health risks when dispersed into air and inhaled.

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Mineralienatlas
  3. ^ Chrysotile on Mindat.org
  4. ^ Chrysotile data on Webmineral
  5. ^ a b "Asbestos" (PDF). Report on Carcinogens, Eleventh Edition. U.S. Department of Health and Human Services. 2005.
  6. ^ Occupational Safety and Health Administration, U.S. Department of Labor (2007). 29 C.F.R. 1910.1001. Appendix J.
  7. ^ Institut national de recherche sur la sécurité (1997). "Amiante Archived 2008-06-25 at the Wayback Machine." Fiches toxicologiques. n° 167. (in French)