Reference work entry
Crocidolite is an asbestos mineral that can be used as a gem. It has a Mohs hardness of five and a specific gravity of 3.02–3.42 g/cm 3. It transforms into petrified wood when subject to SiO 2 metasomatism, and its hardness will increase to 7, but the specific gravity will decrease to 2.64–2.71. Crocidolite can be brownish yellow, reddish brown, grey blue or maroon, has a fine and tough texture, a fibrous structure and silky lustre. A beautiful cat’s eye effect can be achieved through parallel cutting. Therefore, it is a popular raw material for making blue asbestos cat’s eye gems (Fig. 55).
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