GEOLOGY & PLANETARY SCIENCE A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site slate Slate. Credit: Mineral Information Institute A gray to blue, fine-grained metamorphic rock that splits into thin, smooth-surfaced layers. Slate is formed mainly by the metamorphosis of mudstone or shale, in which platy minerals become aligned in parallel planes. It is widely used for roofing tiles. Related category    • GEOLOGY AND PLANETARY SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP