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Transactions of the Royal Society of South Africa. 
the diamond would break, would show signs of holes. Thus, even when 
a cleavage surface exhibits no imprint of a former mineral inclusion, it 
does not follow that the cleavage was not caused by an inclusion. It may 
be surmised, in passing, that the craclied yellow diamond spoken of in the 
last paragraph of Section 11 contained a mineral inclusion.* 
The remarks in the present section apply in the main to more or less 
transparent diamond. Opaque diamond, other than bort, often enough is 
flawed, has little cohesion, and can be easily broken. 
13. Diamond Inclusions. 
Diamonds enclosed in diamonds are not exactly uncommon. There are 
two very fine, nearly white, fair- shaped octaliedra preserved in the De Beers 
office, each containing an inclusion. Both inclusions are practically of the 
same colour as their enclosures : one, a rounded octahedron, is certainly a 
diamond ; the other is probably a diamond, but may be something else — say 
quartz as a remote possibility. These diamonds show very fine colour effects 
under the polariscope, but neither is much flawed internally. Where the 
strain comes from, though, when one diamond encloses another is an enigma. 
Inclusions of diamond in diamond aie not often symmetrical octaliedra. 
One which was almost perfect in outline has been referred to in Section 4. 
A full description of this interesting object, which is still preserved, has 
been given by Williams (p. 506). The majority of such inclusions are 
irregular. A certain piece of Bultfontein cleavage, for example, which came 
from the wash already cracked nearly through, was found, when broken up, 
to contain a venerable-looking and ill-shapen flake of diamond, the cavity in 
which it had been being lined with a soapy-looking substance, possibly 
apophyllite. In this connection it is strange that the apophyllite, or what- 
ever the subslance may be, prefers to stick to the enclosure and not to the 
inclusion. Pretty often in cases of this sort the portions of diamond 
separated by the crack are of different quality and colour. 
Tiny cavities, or what look like cavities, in diamonds are not uncommon. 
They may contain gas. It is not the rule to find any large amount of 
mechanical strain in their vicinity. 
14. Diamonds in the Matrix. 
Bauer tells us (p. 192) that different portions of one and the same 
broken diamond are never found lying close together in the matrix. He 
should have said that he had not heard of such a case. As a matter of 
fact a shattered diamond, mixed up with garnet and olivine, was extracted 
from its kiniberlite matrix in the De Beers sorting office a few years ago. 
Furthermore, on two or three occasions it has happened that a diamond has 
* But diamonds suffering strain, and with visible internal cracks, thovigh 
apparently containing no inclusion, are sometimes met with. 
