Serpentine

Serpentine: A mineral or rock consisting of a hydrous magnesium silicate, H₄ M₃ Si₂ O₉, and having usually a dull green color, often with a spotted or mottled appearance, resembling a serpent's skin. It occurs usually in masses, which are sometimes foliated, sometimes fibrous ... Presence of iron may give it a red or brownish hue. Precious, or noble, serpentine is translucent & of a rich oil-green color. Serpentine results from the alteration of other magnesian minerals, esp. chrysolite, am...