Mineralogy and Geology. . 117 
and lead given in the analysis, as considerably more of lead and less of 
bismuth were found than obtained in the previous analysis by Setterberg. 
The cobalt was considered as due to the cobaltiferous mispickel, which 
with the formula (CoS? + CoAs) + 4(FeS2+-FeAs) would correspond to 
5°61 per cent. In the same manner, the copper calculated as chalvopyrite 
equals 3°67 per cent. These amounts subtracted from the ana ysis, and 
the remainder averaged up, gives for the composition of pure kobellite : 
Ss B P Fe 
17°47 2052 10:43 48-78 755 = 98°75 
Sulphur combined, 473 418 755. 088 = 1734 
Rammelsberg writes the formula, (PbS) BiS?+-(PbS)8SbS3=S 16-82, 
Bi 18:23, Sb 10°54, Pb 54:41 — 100. 
I, Siegenite——A new analysis of the so-called siegenite (Kobaltnickel- 
Kies) from Miisen shows that the earlier analyses of this mineral are errone- 
ous. This is due to the fact that at the time they were made no sufficiently 
accurate method was known for the separation of cobalt and nickel. The 
Separation of these metals was effected by means of nitrite of cobalt. 
Analysis of the crystals, selected as pure as possible from associated chal- 
Copyrite, gave: S 42-76, Co 39°35, Ni 14:09, Cu 1°67, Fe 1°06 = 98-93. 
Considering the iron as combined with 1°21 sulphur and 1-20 copper, 
forming chalcopyrite, and subtracting these from the analysis, the com- 
Position of the pure mineral is as follows : 
: 3 Co Ni Cu 
43-04 40°77 14-60 0-49 
giving the established formula RS+R,8,. The amount of cobalt found 
In former an 
Dot to varying composition of the mineral, although another specimen 
—¢. J. B, 
_ HL Vivianite—An analysis of the vivianite from Allentown, Mon- 
Mouth, Co., New Jersey, gave: 
bg Fe Fe Be | 
G. = 2-68. 28°81 4-96 38-26 28-67 = 100 
Oxygen, 16-23 1-28 8:50 25°48 
The mineral occurred in concentric radiated crystals of a light bluish- 
green color, 
Se Analyses of 
on of Rammelsber 
