Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/49

This page has been proofread, but needs to be validated.
of the red oxyd of Copper and arseniated Iron.
37


SIXTH MODIFICATION.


This modification is the result of a decrease, by which each solid angle is replaced by eight triangular planes, two on each face of the primitive crystal, and inclining on the axis that passes through the angles. Fig. 106; I have not seen this modification as thus described, but only, as in the following figures, in combination with other modifications. The crystal represented by fig. 108 contains all the modifications of the primitive crystal of this substance, which, I believe, have hitherto been noticed.