Online Encyclopedia

BIPYRAMIDAL CLASS (Parallel-faced aem...

Online Encyclopedia
Originally appearing in Volume V07, Page 582 of the 1911 Encyclopedia Britannica.
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BIPYRAMIDAL CLASS (Parallel-faced aemihedral). Here there is a plane of .symmetry perpendicular to the hexad axis; there is also a centre of symmetry. All the closed forms are hexagonal bipyramids; the open forms are hexagonal prisms or the basal pinacoid. The general form Ihikl} is hemihedral with parallel faces with respect to the general form of the holosymmetric class. Apatite (q.v.), pyromorphite, mimetite and vanadinite possess this degree of symmetry.
End of Article: BIPYRAMIDAL CLASS (Parallel-faced aemihedral)
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