Allosigmostaura : Appended Form

Allosigmostaura pseudobisphenoidea

(Pseudo bisphenoidal forms)


Forms belonging to the Allosigmostaura pseudobisphenoidea have as their only symmetry element a 4-fold rotoinversion axis. Crystals of the Tetragonal-bisphenoidic Crystal Class of the tetragonal Crystal System have this basic form. This form can geometrically be represented by an apical 2-fold gyroid bipyramid, in which the composing pyramids are rotated by 900 with respect to each other. No organisms having this basic form are recorded.
For more details and Figures see HERE.

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