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A coarse-grain igneous rock composed of plagioclase Feldspar. Gabbro primarily contains Labradorite, Augite, and Pyroxene. It is sold commercially as a Granite and is used as a building stone. Major commercial sources for gabbro occur in Scotland (Island of Skye), South Africa (Bushveld, Karroo), Canada (Sudbury in Ontario, Labrador), Greenland, and the U.S. (Minnesota, New Jersey, California, New York, Wyoming, Montana). Minnesota Black and Opalescent are brand names for some gabbros.


Synonyms and Related Terms

diabase; norite; trap rock; Minnesota Black; Opalescent; Gabbro (Deut.); gabro (Esp., Port.); gabbro (Fr.); gabbro (Ned.)

Physical and Chemical Properties

  • Mohs Hardness = > 5.5

Resources and Citations

  • Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
  • Robert Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Company, Radnor, PA, 1992
  • C.W.Chesterman, K.E.Lowe, Audubon Society Field Guide to North American Rocks and Minerals, Alfred A. Knopf, New York, 1979
  • 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