The hemiedria is the property of crystals that only have half of the faces that have the corresponding holohedral form.

In a hemihedral crystal, the atoms are arranged in such a way that one of the elements of symmetry disappears. The blender, for example, crystallizes in the form of cubes, but its symmetry is that of a tetrahedron. A truncation of one of its vertices is not repeated in the other seven, but only in three. In the case that these thrushes extend into the mass of the crystal, two conjugate tetrahedra can form, the faces of which do not have the same properties.

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