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Pegmatite with blue corundum crystals

A pegmatite is an igneous rock with a very rough texture, which has large interlocking crystals[1] that are usually bigger than 1 centimeter (0.4 in) and sometimes bigger than 1 meter (3 ft).[2]

Many of the world's largest crystals are found in pegmatites. These include crystals of quartz, mica, beryl, and tourmaline. Some of these crystals are over 10 m (33 ft) long.[3]

Etymology[change | change source]

The word pegmatite comes from the Homeric Greek word, πήγνυμι (pēgnymi), which means “to bind together." This refers to the interlocked crystals in the rock's texture.[4]

References[change | change source]

  1. Jackson, Julia A., ed. (1997). "Pegmatite". Glossary of Geology (4th ed.). Alexandria, Viriginia: American Geological Institute. ISBN 0922152349.
  2. Blatt, Harvey; Tracy, Robert J. (1996). Petrology: Igneous, Sedimentary, and Metamorphic (2nd ed.). New York: W.H. Freeman. p. 73. ISBN 0716724383.
  3. Schwartz, G. (1928). "The Black Hills Mineral Region". American Mineralogist. 13: 56–63.
  4. London, David; Morgan, George B. (2012-08-01). "The Pegmatite Puzzle". Elements. 8 (4): 263–68. doi:10.2113/gselements.8.4.263. ISSN 1811-5209.