os 
196 W. P. Blake on the Mineralogical Curiosities 
are sometimes two inches in diameter. Another variety called 
“boart,” is translucent, and appears to be a confused crystal- 
lization; it accompanies the diamonds of Rio, and is also only 
valuable for its powder. 
The cascatho, a conglomerate, containing diamonds, evi- 
dently corresponds in its origin to the “cement” of gold miners, 
and consists merely of the various water-worn and heavy peb- 
bles accompanying the diamonds in the beds of streams, cemen- 
ted together on the bed-rock by ferruginous, calcareous, or 
siliceous infiltrations, 
The yearly importation of diamonds from 1862 to 1866 has 
averaged 176,000 carats, nearly 1,000 Ibs. troy. Over 400 per- 
sons are constantly employed in cutting diamonds at Mr. Coster’s 
establishment. 
very irregularly compound in their interior structure, none giv- 
ing @ uniform tint in polarized light. 
est mass weighed 13 . Many of the smaller masses 
were highly magnetic, attracting iron filings like magnetite, and 
strong polarity. 
ing strong : 
Native copper with native silver—A mass of native copper 
weighing 1400 Ibs., and resembling the copper of Lake Superior, 
