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Serpentinite is a metaphoric rock, also called Serpentine in older materials and, wider cultural settings, and is not the name of a single mineral. Instead it is a name used for a large group of minerals that fit this generalized formula: (X)2-3(Y)2O5(OH)4, where in this formula, X will be one of the following metals: magnesium, iron, nickel, aluminum,br> zinc, or manganese; and, Y will be silicon, aluminum, or iron. The appropriate generalized formula is therefore as follows: (Mg,Fe,Ni, Mn,Zn)2-3(Si,Al,Fe)2O5(OH)4. Its name originated from the similarity of the texture of the rock to that of the skin of a snake. Chrysotile, antigorite, and lizardite are three of the primary serpentine minerals. There are many other serpentine minerals, most of which are rare. Serpentine minerals form where peridotite, dunite, and other ultramafic rocks undergo hydrothermal metamorphism. Ultramafic rocks are rare at Earth's surface but are abundant at the oceanic moho, the boundary between the base of the oceanic crust and the upper mantle. (Sources: Wikipedia and Geology.com) Photo by Michael Marcotte, of (green) serpentine, with (purple) stichtite areas Return to List Back to Michael's Hobbies page Back to Michael Marcotte's HomePage