Plate 23
Crystals of green corundum in syenite, from Montana
Typical crystal forms of corundum: A the elongated prism with the alternate corners cut by rhombohedral faces, B the tabular prism, C the double pyramid
Crystals of green corundum in syenite, from Montana
Typical crystal forms of corundum: A the elongated prism with the alternate corners cut by rhombohedral faces, B the tabular prism, C the double pyramid