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di-tetrahedral

di-tetraˈhedral, a. Cryst. Obs.
  [f. di-2 1 + tetrahedral.]
  Having the form of a tetrahedral prism with dihedral summits.

1805–17 R. Jameson Char. Min. (ed. 3) 203 It represents a four-sided prism, bevelled on the extremities. Example, Di-tetrahedral tremolite.

Oxford English Dictionary

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