LEUCITE

Leucite

Leucite is a rock-forming mineral composed of potassium and aluminium tectosilicate K2O6'>1. Crystals have the form of cubic icositetrahedra but, as first observed by Sir David Brewster in 1821, they are not optically isotropic, and are therefore pseudo-cubic. Goniometric measurements made by Gerhard vom Rath in 1873 led him to refer the crystals to the tetragonal system. Optical investigations have since proved the crystals to be still more complex in character, and to consist of several orthorhombic or monoclinic individuals, which are optically biaxial and repeatedly twinned, giving rise to twin-lamellae and to striations on the faces. When the ...

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leucite

Noun

  1. A mineral of silica-poor igneous, plutonic and volcanic rocks. Chemically, leucite is a potassium feldspar with insufficient silica to satisfy the chemical bonds. Because of the unfilled bonds, leucite weathers rapidly and can only be seen as inclusions in freshly broken rock.
  2. A leucoplast.


The above text is a snippet from Wiktionary: leucite
and as such is available under the Creative Commons Attribution/Share-Alike License.

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