Did the Ancient Mesopotamian Royal Stone Originate in Oman?

"Royal statuary of the late third and early second millennia BC is often sculpted from „diorite“. But closer examination of the stone reveals that more correctly both diorite and gabbro are manifest. Royal records indicate a source for the „dark stone“ of the statues in Magan/Makkan. This is locatable in south-east Arabia, especially the present-day Sultanate of Oman but also in south-west Iran (Potts 1986: 271-285). Samples of „diorite“ statues arecompared with petrological samples from the Sultanate. The stone of the royal statues need not be exclusively from here since sources closer to Sumer and Akkad exist in Iraq and Iran, although some correspondences are clear between the stone of certain statues and the samples available in the Sultanate."