No. 6.] SANDBERGER — METALLIC VEINS. 357 



Mine near Weilmuenster, and Weyer near Runkel). Where 

 the diabase became compact and fresh in the depth the veins 

 were compressed into a simple crack filled with clay and barren 

 of ore. Lead, zinc and arsenic were found by Senfter in Nassau 

 diabases ; therefore it cannot be wondered at if, under favourable 

 circumstances, they concentrate themselves into ores. But still 

 more striking is the connection between ore-bearing and the con- 

 stitution of the neighbouring plutonic rocks at St. Andreasberg 

 in the Harz. Here the clay-slates through which the veins of 

 ore run are bounded on the north by granite and to the south 

 by diabase. The augite of the latter contains, as mentioned 

 above, more lead than copper, more antimony than arsenic, more 

 nickel than cobalt ; all of which corresponds to the distribution 

 of these elements in the veins of ore. I have not yet tested this 

 augite for silver and zinc ; but I shall repeat my tests as soon as 

 sufficient material reaches me. The latter metal was determined 

 by Marx in 1868 to range from 0.0007-0.0014 per cent, in 

 Central American hornblende-and augite-andesites. The occur- 

 rence of zeolites (analcime, chabasite, stilbite, apophyllite), 

 otherwise unusual in metallic veins, but not rare in clefts of 

 diabases, forms an additional and not unimportant argument in 

 favour of the derivation from decomposed diabase of the 

 solutions that are precipitated in metallic veins. The above- 

 cited facts have fully established of what vital importance the 

 contents of the augite in heavy metals are for the explanation of 

 the mode of filling of the metallic veins in diabases and similar 

 rocks. 



Not only do the augites of the elder volcanic rocks contain 

 heavy metals, but they have been found by me also in the 

 younger and youngest such rocks ; so also for instance the occur- 

 rence of cobalt and nickel in the nephelinite of the Katzenbuckel 

 by Rosenbusch, of copper and bismuth in the basalt of the Schif- 

 fenberg near Giessen by Winter and Will, of lead in the basalt 

 of Annerod by Engelbach and of arsenic and antimony in that 

 of the Kaiserstuhl by Daubrde. 



With time mettallic veins might form themselves also out of 

 such rocks. At the present time in volcanoes also are the con- 

 tents of augites in heavy metals sometimes very apparent. 

 For the occurrence of copper-and lead-compounds in the lavas 

 and fumaroles of Vesuvius and other volcanoes must always be 

 ascribed to the augite's contents of these metals, which have 



