GLUCINA. 
377 
of Figs. 409, 410, 411 and 412. In Fig. 
409, two opposite shorter terminal edges 
are replaced by the plane i. The striae 
being perpendicular, and the axis of re¬ 
volution being parallel to the edge formed 
by the meeting of the planes T and i, a 
revolution of 180° would give the form 
Fig. 401. Two of these crystals would 
give the right rhombic table represented in 
the lower part of Fig. 404; and again, 
three of these form the regular six-sided 
prism. The crystal 402 is in like manner formed by a similar revolution of a crystal like 
that represented in Fig. 410, in which all the shorter terminal edges are replaced by the 
planes i, being a crystal of the same form as Fig. 399. The two crystals Figs. 401 and 402 
will produce the form Fig. 403, and three of the latter united give that of the six-sided prism 
Fig. 405. In Fig. 407, one of the crystals is wanting. Six of the forms Fig. 402 give that 
represented by Fig. 406, which is occasionally observed at this locality. The compound 
crystal Fig. 408 is marked by striae as represented in the cut, and I suppose it to be produced 
by the union of four crystals similar to those represented in Fig. 401, and two formed by the 
revolution in the direction of the dotted line, Fig. 411, so as to give that represented in Fig. 
412. The angles of all these crystals, whether single or compound, are 60° and 120°. 
Fig. 413. 
Min. — Part II 
Fig. 413 is introduced from Shepard’s Mineralogy. It is more rare 
at the Greenfield locality than either of the preceding. According to 
that author, in this case three prisms, similar to Fig. 410, cross each 
other, and the prisms project at each end beyond the face of compo¬ 
sition. It will be observed that the direction of the striae is different 
from that in the preceding figures, and I infer therefore that its com¬ 
position is different. 
In Connecticut, chrysobcryl occurs at Haddam, where it is asso¬ 
ciated with the minerals for which that locality is so celebrated. 
48 
