Mineralogy and Geology. 271° 
quartz vein exists, and the rock of the hill is profitably worked; some 
forty tons per diem are crushed, yielding from two to twenty dollars per 
ton—averaging from five to six dollars per ton. 
12, On the Crystalline form of Pachnolite; by A. DesCuorzeaux. 
Calculated, ry 
m on m in front, ==. 98° 34’ 98° 40’ 
. on w lateral, = 81 26 ; y ¢ macle 
+ on 53 (planes 4 in figure) adjacent, = 108 15 
6} on $¢ tacent = 94 13 94 13 macle. 
moi adjacent, © ee Os Blk 
$9 on b} opposite, 52 46 52 46 
Edges °! : ™ adjacent, = 146° 45/ 
by m 
Base p:m = 90 20 
Plane single of ‘the basi 98 33 547 
Plane angle of the lateral faces, 90 16 48 
The plane of the optic axes is perpendicular to the plane of symmetry, 
m 
and makes an angle of about 10° to 15° with a normal to the edge ts 
and an angle of about 23° 15/ to 18° 15’ with a normal to the edge a 
One of the bisectrices is normal to the plane of symmetry; the other 
makes with the edges ” and bb the same angles as the plane of the 
m 
crystals rest upon small, translucent, erystalline lamine, which appear 
possess different optical properties. Is this mineral 2 These 
ake a transition stage between cryolite and pachnolite, 
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