diamond crystals
Diamond Crystals
The diamond octahedron
has the shape that we describe as a diamond. While it is the most
common
shape for a diamond crystal, cubes, dodecahedra, and combinations of
these
three shapes are common. All are highly symmetrical, with equal
dimensions
in three perpendicular directions, and all are manifestations of the
cubic
crystal system to which the mineral diamond belongs.
Exceptions are the flat form called a macle, which is a twin, or composite crystal, as if mirrored across the middle, and etched crystals, with rounded surfaces and, sometimes, elongated shapes. The shapes of diamond crystals can be very intriguing.
These triangles result from subtle changes in
height on a diamond's octahedron face and are called trigons. The
trigons
shown here are indentations, probably produced by natural etching of
the
crystal. The image was created with Nomarski differential interference
contrast microscopy and is 0.29 mm across.