When often repeated on the same plane, the twinning is said to be “polysynthetic,” and gives rise to a laminated structure in the crystal.

If we pass to an isolating language like Chinese, we find the exact converse of that which meets us in the polysynthetic tongues.

Twinned crystals are not common, but the presence of polysynthetic twinning is sometimes shown by fine striations running diagonally or obliquely across the cleavage surfaces.