Mineral Species: Chrysotile

Chemical Formula: Mg3Si2O5(OH)4

Chemical Name: Magnesium Silicate Hydroxide

Mineral Class: Phyllosilicate

Mineral Notes: Chrysotile belongs to the Asbestiform group of silicates together with several other minerals. Their common property is to form thin fibres which can be teased out and woven into a flexible sheet, making these useful for heat insulation. The fibres, however, have a tendency to break and if inhaled can lead to a fatal lung disease Asbestosis. There are three known varieties of Chrysotile: Clinochrysotile (which is monoclinic), Orthochrysotile (which is orthorhombic) and parachrysotile (which is an orthorhombic polymorph). To some degree the chemical varience depends on the substitution of Magnesium by Iron.

Description: Thin bands of Chrysotile embedded in black matrix. The bands are easily seen to be formed of fused upright crystals. Because they are thin, the crystals refract light strongly, which means that the bands are very chatoyant under illumination. They become very gemmy. The latter property makes this an extremely attractive display specimen.

Location: Pietroasa, Bihor, Romania.