Editing Slate (section)

== Terminology ==
Before the mid-19th century, the terms "slate", "[[shale]]", and "[[schist]]" were not sharply distinguished.<ref>{{cite book|first=R. W. |last=Raymond |chapter=Slate |chapter-url=https://books.google.com/books?id=FpqFAAAAIAAJ&pg=PA78 |title=A Glossary of Mining and Metallurgical Terms |publisher=American Institute of Mining Engineers |date=1881 |page=78}}</ref> In the context of underground [[coal mining]] in the United States, the term slate was commonly used to refer to shale well into the 20th century.<ref>{{cite book|first=Albert H. |last=Fay |chapter=Slate |chapter-url=https://books.google.com/books?id=y6hCAAAAIAAJ&pg=PA622 |title=A Glossary of the Mining and Mineral Industry |publisher=United States Bureau of Mines |date=1920 |page=622}}</ref> For example, roof slate referred to shale above a [[coal seam]], and draw slate referred to shale that fell from the mine roof as the coal was removed.<ref>{{cite book|editor-first=J. Marvin |editor-last=Weller |url=https://books.google.com/books?id=6UIrAAAAYAAJ&pg=RA1-PA18 |title=Supplement to the Glossary of Geology and Related Sciences |publisher=American Geological Institute |date=1960 |page=18}}</ref>

The [[British Geological Survey]] recommends that the term "slate" be used in scientific writings only when very little else is known about the rock that would allow a more definite classification. For example, if the characteristics of the rock show definitely that it was formed by metamorphosis of shale, it should be described in scientific writings as a metashale. If its origin is uncertain, but the rock is known to be rich in mica, it should be described as a [[pelite]].<ref name="BGS"/>