scattered,
but cloudy and less distinct. In the pure white brilliant stones of
India, it is decidedly black, and abruptly distinct in formation. Why
the carbon inclusions failed to crystallize with the surrounding
diamond, has not been satisfactorily explained. As they must have been
subjected to the same heat and pressure as the remainder of the
crystal, some other agency whose power was not equally distributed
during the process of crystallization probably failed; again it may be
necessary for the crystallization of carbon that it should be in a
certain specific condition when the heat and pressure assumed to be
requisite are applied. Rapid chemical action whereby carbon in solution
is thrown down in transparent crystals, might surround particles which
had escaped the solvent; on the other hand, the same result might be
attained by the slow accretion of crystallized carbon atoms from a
surrounding composite, to a nucleus of the element.
Sometimes
these inclusions look like rough jagged pieces of carbonado, frequently
surrounded by smaller detached pieces, but more often they resemble ink
spots. Occasionally they appear like a thin cloud, as if a black powder
were sprinkled over the face of a small fissure in the grain of the
crystal. Some of them are fuzzy looking clusters, like little bunches
of black dust. In other cases they appear as sharp hair lines, usually
very short, occasionally broken at right angles, T shape, or like a
check mark.
Small
diamonds have been found in larger crystals. This fact, and the
statement that the bursting of crystals is due to inclusions of
compressed gas, led Mr. Williams to question the igneous theory of the
genesis
