RI ET 
Mineralogy, Geology, &c. 45 
stone ; these cavities are often brilliantly es with them, 
and doubtless it arose from their fa ing out by the disinte- 
gration of the rock that the > aiistal were formerly found, on 
the shores of the island and in the water. At present they 
are scarcely obtained at all except by breaking the rocks. 
The immediate matrix of the crystals seems to be a mixture 
of fine granular quartz with the limestone ; it is impressible 
by steel, but sometimes does not input with acids.* The 
crystals of this locality are of the c on form, very lim- 
pid, and often contain a dark sclahant were substance i im- 
bedded in them. 
Crystals of calcareous spar, well defined and of considera- 
ble size occu occur in the same rocks, sometimes with the a 
pear se 
ion of the rhomboidal varieties. ae 
Very brilliant rhombic masses of calcareous spar also ios 
sent themselves in these rocks; these masses are not erys-_ 
tals, but have the crystaline structure, giving perfectly rhom- 
boidal fragments with a high pea rly lustre ; they are very 
white and appear exactly like the Iceland crystals, only 
they are not transparent. They seem to be the bitterspath. 
‘The poor people on the island had no idea that the calcare- 
ous crystals were of any value, and had been in the habit of 
throwing them away; we took care to give them a different 
impression, and trust it may be useful to future WisitORss..: 
Crystals of Diamond Point. We passed down the nile 
iength of the lake, (thirty-six miles,) in a very small open 
boat—a fisherman’s skiff, rowed by two men. We stopped 
at a place on the north ahote of the lake, called Diamond 
Point, from the fact that crystals are found ‘also at this place. 
It has been recently opened by the man who lives on the 
island, and who was our guide on the present occasion. — 
The and its associated minerals are the same as on the 
ree » only we observed a see vanely of siliceous mine- — 
; agate—ele-_ 
os cavities occupied by quartz erystals; and some singular 
d portions, concentric and curved | like agate, but — 
zy 
%* Te 7 Zr. : : a¢.,11. aoe 3. 
" Seiacl 
