470 
MEASUREMENTS OF CRYSTALS, 
CALCAREOUS SPAR. (Continued.) 
P on c . 135° O' 0" 
P on m . 149 2 11 
P on r or r' . 151 2 40 
Pons . 119 2 11 
c on r or c' on r .. 152 6 50 
g on i .. 112 10 0 
g on s . 127 52 30 
m on s or m' on s' _. 121 32 54 
m on s' or m' on s .. 154 39 13 
s ons .. 63 44 55 
s ons' _ 116 15 5 
t ont ... 137 39 26 
Fig. 83. A twin from Haverstraw, Rock¬ 
land county. Angle of revolution 
60°. 
CALCAREOUS SPAR. 
Fig. 89. A twin similar to that represented 
in Fig. 79, but with the additional 
planes t. 
Fig. 90. A twin from Haverstraw, Rock¬ 
land county. Face of composition 
parallel with a plane passing through 
the vertical axis : angle of revolu¬ 
tion 180°. 
Fig. 91. Two solid angles of the primary 
rhombohedron replaced by tangent 
planes. 
Figs. 92 and 93. Twins of the preceding. 
Fig. 94. A twin from Rossie, St. Law¬ 
rence county. 
