breaking up of a large crystal, yet in only one instance have pieces been found which could be fitted together, and these occurred at different levels. Does not this fact point to the conclusion that the blue ground is not their true matrix ? Nature does not make fragments of crystals. As the edges of the crystals are still sharp and unabraded, the locus of formation cannot have been very distant from the present sites. There were probably many sites of crystallisation differing in place and time, or we should not see such distinctive characters in the gems from different mines, nor indeed in the diamonds from different parts of the same mine.
I start with the reasonable supposition that at a sufficient depth * there were masses of molten iron at great pressure and high temperature, holding carbon in solu-
* A pressure of fifteen tons on the square inch would exist not many miles beneath the surface of the earth.
