Wollastanite

This specimen shows layering of different kinds of rock, leading to its classification as a metamorphic rock. It is classified as wollastonite skarn from New York. It is on display at the Smithsonian Museum of Natural History and is described as limestone which was metamorphized during the continental collision 1.1 billion years ago. It is actually the white crystals which are described as wollastonite, and other contents include garnet and diopside. The wollastonite is used to reinforce plastics and stabilize ceramics.