An abundant sedimentary rock consolidated from layers of clay and mud. Shale has very fine grains and a laminated structure that fractures easily along the bedding lines. The stone is soft, smooth, and can feel greasy. Shale is composed of clay (>30%) and silica along with smaller quantities of carbonates, feldspars, iron oxides, fossils, and organic matter (called shale oil). Shale oil, or kerogen, is a sulfurous hydrocarbon that can be refined as a source of fuel. Shale can vary in color from gray, brown, black, green, or red. Shale is used in the manufacture of ceramics, tile, and brick. It is also a source of alumina for portland cement.
Synonyms and Related Terms
layered mudstone; skifer (Dan.); Schiefer (Deut.); schiste (Fr.); schalie (Ned.); argilito (Port.)
Sources Checked for Data in Record
- Encyclopedia Britannica, http://www.britannica.com Comment: "shale" Encyclopædia Britannica [Accessed January 22, 2002].
- C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
- Wikipedia, the free encyclopedia, at http://www.wikipedia.com Comment: http://en.wikipedia.org/wiki/Shale (Accessed Nov. 9, 2005)
- Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
- Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 703