No. 6.] SANDBERGER — METALLIC VEINS. 361 



smaltine veins of Bieber, in many places also (Alzenan, Sommer- 

 kal, etc.) stringers of copper ore have been found, which contain 

 principally copper pyrites, but also locally bornite and cobaltous 

 tetrahedrite. The latter mineral, which was first closely examined 

 by me in 1862, occurs evidently in the stringers of those gneisses 

 whose micas contain all the above-mentioned elements — but cop- 

 per, iron and sulphur in excess over cobalt and arsenic. Galena, 

 as far as I know, has never been found in the Spessart. All the 

 more frequently is it found, either with or without copper pyrites, 

 in the vein-region of the neighbourhood of Schapbach, the mica 

 of whose gneiss contains copper, lead and bismuth. Antimony 

 and arsenic were not discoverable in the mica, and occur only in 

 minimal traces in the veins bearing galena : the former in the 

 very rare antimoniate of lead, the latter in mimetisite, green lead 

 ore (0.61 arsenic acid, Petersen), and in roselite, which was ob- 

 served only once in very slight quantity. The latter mineral and 

 the equally rare heterogenite seem at the first glance alone in 

 the metallic vein to represent the cobalt repeatedly observed in 

 the mica j but the galena also contains cobalt, nickel and bis- 

 muth, which have been precipitated here along with the ore that 

 is present in the greatest quantity, in precisely the same way as 

 elsewhere with magnetic pyrites. A great number of veins of the 

 Black Forest are filled in the same way ; but others, viz., those 

 of the region of Geroldseck and of the Muensterthal contain, 

 along with galena, much blende and no copper pyrites ; there- 

 fore we may infer that they obtained their metals from mica 

 rich in zinc and free from copper. In respect to the veins of 

 Wolfach, Welschensteinach, etc., which are rich in antimony and 

 silver, I must not express any opinions until I have examined the 

 micas of the country-rock : possibly they will give results similar 

 to those from the augite of Andreasberg. 



The marked contrast between the ore-districts of the gneiss of 

 Schapbach and the granite of Wittichen, which are scarcely five 

 miles apart, is explained by the composition of their micas. 

 That of Wittichen is free from lead, but contains silver, arsenic, 

 bismuth, cobalt, nickel and a little copper, viz., all the elements 

 that occur in the metallic veins there ; towards the west they 

 are united to a cobaltous tetrahedrite, but in the east are sepa- 

 rated into native silver, cobalt-nickel ores and copper-bismuth 

 compounds. 



As we may observe, these investigations, which could not be 



