True about mounting stones is: (A) Fast setting, (B) High expansion, (C) High strength, (D) All of the above
Answer is A. The use of an articulator makes it necessary to mount the casts using a gypsum-producing product. These materials are referred to as "mounting" stones or plasters. They are fast setting and have low setting expansion. The mounting plaster has a sufficiently low strength to permit easy trimming and facilitate separating the cast from the articulator mounting plates.
Phillips Science of Dental Materials ed 12 pg 191