No. 6.] SANDBERGER — METALLIC VEINS. 355 



can separate out from them ; and this is certainly the reason 

 why certain cobalt veins at Annaberg always grow considerably 

 richer where they intersect hornblendic schists. Up to the 

 present time I have come to no definite conclusion as to whether 

 the pyrites that occur in quantity in the hornblendic schists (e. g. 

 near the Gutach-Muendung, not far from Hausach in the Black 

 Forest), and sometimes in particles as large as peas, separated 

 out immediately on the formation of the rock, or were first formed 

 subsequently, but I am inclined to believe the former, because 

 the pyrites appear firmly grown together with perfectly fresh 

 mica and hornblende. In these pyrites, which consist principally 

 of magnetic pyrites accompanied by only a little iron and oopper 

 pyrites, Petersen, who examined them at my request, determined 

 on the average: S 39.93, As 0.15, Pb 0.10, Cu 0.36, Fe 58.31, 

 Ni and Co 0.63, Ti and Mn trace, Bi and Ag slight traces. 



The pyrites contain the heavy metals also in much the same 

 ratio in which I have found them in hornblendes free from 

 pyrites. 



Several varieties of augite were examined, but naturally only 

 such as form elements of rocks. The following results were 

 obtained : 



1 . Augite out of a stream of 



the Somma, near Cisternal Cu and Co evident. 



2. Augite in the porphyritic 

 basalt from Liebhards inter- 

 crystallised with hornblende No. 



1 : powder dark greenish-gray. Cu comparatively much ; 



apparently enough to de- 

 termine quantatively ; Co 

 plain (along with much 

 " Mn). 



3. Augite of the porphyritic 

 basalt from Dckardtsberg, near 



Breisach : * powder light-gray. Cu no reaction. 



Co evident. 



4. Augite of the angite.por- 

 phyry of the Fassathal : powder 



clear greenish-gray.* Cu no reaction. 



Co evident. 



• There were only a few pure crystals to be had. 



