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much what would be obtained if two rough flakes, not necessarily of equal 
thickness — one from each of two opposite faces of an octahedron, or one 
from each of two opposite corners of a rhombic dodecahedron — were rotated 
60° or 180°, either way round, and joined together. At the same time the 
opposite faces tend to accurate parallelism. Since very few diamonds have 
sharp edges it can be understood why the majority of diamond macles have- 
not indented (swallow-tail) corners, the indentations having disappeared 
in the process which rounded the edges. Hence the corners of most of these 
macles are blunt ; though not a few, and especially those with dodecahedral 
characteristics, taper gradually with a lenticular section to a sharp edge. 
An uncommon sort of made is known in which the central plane is not a 
hexagon but a perfect triangle larger than the parallel faces, and every- 
where falling outside the orthogonal projection of the faces ; and in this 
case (which is difficult to understand) the edge faces meet in fairly sharp 
edges and carry the usual facial triangular indentation (see Fig. 1).* 
Pretty often one of the halves of a made projects beyond the other, as 
though the two halves had worked to combination planes of different size, or 
as though a flake from one diamond had been joined at random, excepting 
as to orientation, to a flake from another larger one. Fig. 2 is an illustra- 
tion of a Wesselton made of this kind. In Fig. 2 (a), CB and CF are the 
two halves seen edgewise. The projecting portion AD of the twinning plane 
is indented with shallow triangles standing the opposite way to those on 
the outer face EF, as shown in plan in Fig. 2 (b). That is to say, the lower 
half CF in Fig. 2 (a) partakes of the character of a proper octahedral 
tabular crystal. We should infer from this that either half may have grown 
independently of the other to some extent. 
Fig. 3 shows an edge of a Bultfontein made of a type intermediate 
between those of Figs. 1 and 2. 
Frequently the edges of glassy macles are deeply indented with pyramidal 
terraced depressions, the triangles of one half being opposed base to base 
to those of the other half. Quite as often, however, only one of the halves 
has these depressions, the other half being quite independent of them. 
* According to current theories this specimen would be regarded as a macled form 
of the plus and minus tetrahedron. Cf. Spencer, ' Ency. Brit./ 1910, art. " Crystal- 
lography " ; and Eutley's ' Mineralogy/ 1916, p. 70. 
Fig. 1. — Wesselton glassy made, enlarged six times. 
