Mineralogy and Geclogy of Nova Scotia. 273 
the primary obtuse rhomboid, sometimes so modified, as to as- 
sume the lenticular hemitropic form represented in Phillips’s 
Mineralogy, p. 138. At other times, from the almost innumerable 
faces of composition, they become indescribably complex, or at 
least would require, for a precise crystallographic description, the 
consummate skill of a Haiiy, a Mohs, or a Brooke. They are 
slightly striated, of a glistening vitreous lustre, and often hemi- 
tropically united. This chabasie agrees in all characters, excep- 
ting color and complexity of modification, with that from the 
Scotish Islands. 
The analcime is m white, opake crystals, exhibiting the pas- 
sage of the primary cube into the trapezohedron, which it fre- 
quently completes, and thus forms crystals having twenty- 
four equal and similar trapeziums which entirely obscure the 
primary planes. 
Over the analcime, the heulandite is thickly implanted in 
small, but extremely brilliant, pearly-white crystals, which are 
transparent or translucent, and usually in the primary form, some- 
times slightly modified. 
The calcareous spar is crystallized in very acute rhomboids, 
of which scarcely two can be found possessing similar angles. 
The crystals are likewise so modified, as to assume the form of the 
dodecahedron composed of two scalene six-sided pyramids, ap- 
plied base to base. They are greatly elongated, and grouped in 
delicate stelle, occupying the cavities of the amygdaloid. 
Delicate prismatic crystals, but not of sufficient size to enable 
us to determine their form, resembling the Brewsterite from Scot- 
land, occur scattered through the cavities of the trap-tuff and 
associated with perfect and distinct crystals of analcime, constitu- 
ting interesting specimens. 
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