serpentine - teaching hand specimen from the Melones fault zone
Serpentine is a mineral formed by the metamorphism and igneous activity associated with subduction zones, where an oceanic plate is diving below a continent. It is derived from the metamorphism of magnesium-rich peridotite from the mantle. It's the state "rock" of California. Its chemical formula is Mg6(Si4O10)(OH)8
Serpentine's structure is sheets of silica tetrahedrons sandwiching layers of magnesium hydroxide. The magnesium hydroxide layers imperfectly stack with the silica tetrahedron sheets, causing bending of the layers. In most serpentines, these layers form convoluted sheets, well represented in these examples. When the sheets bend into tubes, fibers of asbestos are formed.
These textbook specimens were collected from the Melones fault zone in the American River Canyon, Placer County, California, right in the Forty-Niner gold belt. They are glossy dark green and say "squeezed" to a student.
Select a specimen: If more than one specimen is shown, you can select a particular specimen by telling us what is in the photo with it, a black and silver pen, a black mechanical pencil, a blue and silver pen, or one of those plus some number of coins, or you can let us make the selection.
Shipping: in a First Class package unless combined with other items. Click > here < for shipping rates. Use back button to return to this page.
Making multiple purchases? Click on the "combine shipping" button in the shopping cart. We'll send an invoice with combined shipping. A link in that invoice will bring you back to checkout, no hassle.