Slate of finished and unfinished slate has increased. It has slate in various colors. Deposits of slate exist throughout the Australian continent, with large reserves quarried in the Adelaide Hills (Willunga and Kanmantoo) and the Mid North (Mintaro and Spalding). Because slate was formed in low heat and pressure, compared to a number of other metamorphic rocks, some fossils can be found in slate; sometimes even microscopic remains of delicate organisms can be found in slate. Slate Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional
Slate types of object made from slate rock. It may mean a single roofing tile made of slate, or a writing slate. These were traditionally a small, smooth piece of the rock, often framed in wood, used with chalk as a notepad or noticeboard, and especially for recording charges in pubs and inns. The phrases "clean slate" and "blank slate" come from this usage. Before the mid-19th century, the terms "slate", "shale" and "schist" were not sharply distinguished. In the context of underground coal mining in the United States, the term slate was commonly used to refer to shale well into