Mineralogy and Geology. 271 
14. On a new variety of Spinel; by H. Sr.Cratre Devitie.—A black 
spinel with low pyramids in has of the octahedral Planes, and the faces 
rounded, has been found in the rock of At | Lherzolite. Most 
of the crystals, however, are cctahiedions jib rounded beveled edges 
and eroded faces. The crystals are 5 to 10 (rarely 20) millimeters in de 
ameter; and though mostly black are war eaman reddish-br 
3°871 for the black; 3-868 for the reddish-bro Analysis by Deville 
gave 4159-06, Fe 10: 72, Fe 18°60, Mg 17: 20—-100" 58, whence the formula 
Cee Fe)(2l, He), as in true Plecnanie, —Les Mondes, J uly 12, p. ship 
5. Origin of the Diamon . B. pe Cuancourrors has presented 
‘ie view that the diamond has hace formed from hydrocarburetted ema- 
nations, as sulphur is formed from hydrosulphuretted emanations, and 
that its origin is thus connected with the previous existence of petroleum- 
bearing or bituminous schists. In the oxydation of sulphuretted hydro- 
gen in solfataras, all the hydrogen is oxydized, but only part of the sul- 
phur passes to the state of sulphurous acid in this humid process of com- 
bustion. So, in an analogous manner, the diamond was probably formed ; 
a 
in which all the e hydrogen was oxydized, but only a part of the carbon 
was transformed into carbonic acid. This view accords with the occur- 
rence of the diamond in arenaceous rocks or itacolumites, which are 
mostly metamorphic rocks of paleozoic age, and which may have once 
been bituminous either by original formation or by emanations from 
that of the metamorphism to which the ae Oi rocks have 
SENET ti been subjected, and which may have been essential to the 
an 
6. Paragenesis of Minerals—Revss has a paper of great interest in 
the Berichte of the Vienna Academy for Jan. 7, 1863, on the associa- 
tions and superpositions 0: of the various minerals at Przibram, with refer- 
€ 
The great number of metallic ores and other ee: in that noted mining 
on makes it especially instructive in this 
cats Cassiterite, Declan from Montebras in rance has been found 
by Capt. Carron to contain two to three per cent of niobic and tantalic 
acids, and in some cases even five per cent, and he says that the ore may 
used for obtaining these rare me' etals. 
Cassiterite is found in the Temeschal Ranche, in Los Angeles Co., Cali- 
-_ rnia, at sever val points, with some promise of economical valed. It 
some cases with a ferruginous eeerreto rock, or a very 
black com aa hornblende in granite and qua 
Wood-tin has been oy near Eooasille, Owhyhee Co., Idaho 
arryes by Walter Gibson of N or. 
8. Analyses fae — i; (communizated by S. B. Sparxten.—(1.) 
e from Delaware Co., Penn, rock is 
nilekeceramen: Teen nen ivaacin ane and from half 
