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466.12
The three balls on the top can be lifted as a triangular
group and rotated 60
degrees in a plane parallel to the seven balls of the
hexagonal equatorial set below them;
this triangular group can be then set into the three
previously vacant and bridged-over
valleys. As this occurs, we have the same 12 spheres
closest packed around one with an
overall arrangement with the two triangular sets of
three on the top, three on the bottom,
and six around the equator. The top and the bottom triangular
sets act as poles of the
system, which__ as with all systems__ has inherent free
spinnability. In both of the two
alternate valley occupations the northern polar triangle
is surrounded alternately by three
squares and three triangles, reading alternately__ triangle,
square, triangle, square,
triangle, square.
(See Fig. 466.13B.)
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