noun
: a twin crystal in which the individuals are so related that one can be made to coincide with the other by a rotation of 180 degrees or occasionally 60, 90, or 120 degrees — compare reflection twin
noun
: a twin crystal in which the individuals are so related that one can be made to coincide with the other by a rotation of 180 degrees or occasionally 60, 90, or 120 degrees — compare reflection twin
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012