ei mee » Rutilated Quartz Crystals from Vermont: _ 
ca _which had ¢ come: to the knowledge of Mr. Alger, were those men- 
“tioned and figured by Dr. McCulloch, and described in vol. ii, 
" 4 of the Geo ological Transactions of London. But in this case, the 
¥ substance. was chalcedony, 3. 
as and. the imbedded masses 
which. appear on the acumi- STRIATED QUARTZ CRYSTALS. 
‘nating planes of the crystals, and are parallel with their edges of 
combination with the adjoining planes, as shown in the figure be- 
low. They are usually mere superficial ee lines so slightly 
impressed as to be visible only when held in a par rticular position 
in regard to the light ; but in a few cases, these configurations, com- 
“mencing at a small point before the — had attained its full 
size, continue to widen with ev- 
crystal, until they produce cav- 
ities of considerable depth. That 
they were formed in this man- 
ner, is indicated by shi step-like 5 
appearance of the sides of these 
appeared. No substance having 
such form, has been found at- 
tached to any of the crystals from this place, and although the 
angles at which the sides meet each other, (about 7 72° and 108°, )* 
are nearly those of calc spar, or carbonate of iron, it is evident 
from the enlargement of the cavity towards the surface of the 
crystal, or the hopper-like appearance“assumed by it, that neither 
mage These angles were incorrectly a in the published — of the Amer- 
= its Association. ey have now — sbtalbed: by measuring the casts taken from 
= cavity, instead of the cavit y itse 
Szcoxp Sznies, Vol. X, No. 28 = 1850. 3 ’ 
anne 
ttn as 
2 % 
ve hie ea ae 
