(geometry, mineralogy, crystallography) A polyhedron having twelve sides, each in the form of a scalene triangle, that is topologically equivalent to a hexagonal bipyramid and whose middle section can be said to inscribe a rhombohedron.
1907, Benjamin K. Emerson, Joseph H. Perry, The Green Schists and Associated Granites and Porphyries of Rhode Island, US Geological Survey, Bulletin Number 311, page 24,
Other steep scalenohedrons of the principal zone are also often present, sometimes in addition to y, sometimes taking its place.
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