Mineralogy of asbestos from the metamorphic complex from north easternTakab-NW Iran

The ultramafic rocks from the Takht-e-Soleyman metamorphic complex, in Precambrian age, are classified as serpentinized metaperidotites and serpentinites, based on degree of serpentinization. Serpentine forms more than 90 volume% of the serpentinites. On the basis of serpentine polymorphs, textural relations and micro-structure features, variety of serpentinites are determined as massive serpentinites, serpentinite schists and chrysotile-bearing serpentinites.  Chrysotile in serpentinites has been formed due to static condition and brittle deformations. During static state chrysotile and lizardite after olivine and pyroxene are formed as pseudomorphic mesh and bastite textures in the massive serpentinites. Then serpentinization processes reactivated by formation and development of joints and fractures related to brittle deformations at the local sheared zones. Chrysotile occur as fine grained crystals in the serpentinite matrix and veinlets with mm thickness filling fractures of the chrysotile-bearing serpentinites. Sligtht thickness of chrysotile veinlet in the investigated serpentinites can be attributed to the olivine rich composition of protolite. Low amounts of Cr2O3 in composition of the analyzed chrysotile supports low clinopyroxene and high olivine in protolite of serpentinites. Serpentinite schists are formed under ductile deformation condition at the regional sheared zones. Amphibole asbestos occur as veins having meter scale thickness filling of joints and fractures at the regional sheared zone. Length of thin and long asbestos amphibole arrives up to cm. On the basis of petrography, raman spectroscopy, XRD and microprope analysis, both chrysotile- and amphibole asbestos have been recognized in the Takht-e-Soleyman serpentintes.