Mg₃Si₂O₅(OH)₄ commonly known as "white asbestos" is the only fibrous form of the serpentine mineral group, and is the most commonly used type of asbestos accounting for approximately 95 % of the asbestos found in buildings through out North America.

From the Greek chrysos - "gold" and tilos - "fiber." a=1.569, g=1.57

Lizardite (plate like structure non-fibrous)and Antigorite (fibrous form Picrolite)

Chrysotile
Dispersion Staining HD 1.550
Positive Sign of Elongation Crossed Polars / First Order Retardation Plate
Anisotropic Crossed Polars