No. 6.] SANDBERGER — METALLIC VEINS. 353 



of nickelous oxyd increases in the same ratio as the transforma- 

 tion of the lime-olivine into serpentine progresses. In the stone 

 of the Black Rock near Tringenstein, which contains 20 per cent, 

 lime-olivine to 40 per cent, serpentine, it amounts to 0.162 per 

 cent : but in that of the Huelfe Gottes Mine near Nanzenbach. 

 with only some seven per cent, lime-olivine and 50J- per cent, ser- 

 pentine, it already reaches 0.666 per cent. In the fresh rocks, 

 so far as known, no nickel deposits occur, but only in the highly- 

 decomposed. In the greatly serpentinised palaeopikrite of the 

 Huelfe Gottes such a deposit has been mined for twenty years, 

 whose ore according to Casselmann, is a mixture of bitterspar, 

 ferrous carbonate, copper pyrites (21.98 per cent.=7.60 per cent, 

 copper), millerite (6.68 per cent.=2.64 per cent, nickel), sul- 

 phuret of bismuth (2.05 per cent.), iron pyrites (7.72 per cent.) 

 with 0.30 per cent, quartz and red hematite ; but the relative 

 quantities of the sulphurets vary so much that ores occur also 

 with almost equal percentages of nickel (6.13) and copper (5.39). 

 Both here and in the entirely similar ore-deposits of Belln- 

 hausen near Gladenbach (as I have already shown) there is no 

 doubt that the slight percentage of nickel in the palaeopikrite 

 has been concentrated and precipitated by contact with sulphur- 

 etted fluids, and in this way has yielded workable quantities of 

 ores of nickel. In the geodes nickel pyrites is always the sul- 

 phuret last deposited : a phenomena that recurs in many other 

 metallic veins (Joachimsthal, Andreasberg, Huckelheim and 

 Bieber in the Spessart, etc.) and is connected with the com- 

 paratively ready solubility of the sulphuret in sulphide of ammo- 

 nia and similar soluble sulphur-compounds of alkalies and alka- 

 line earths. It is overlaid only by calcspar, which mineral, 

 moreover, occurs also in small stringers that intersect the ore- 

 deposit and contain arsenical nickel and smaltine. It is a familiar 

 fact that cobalt concentrates itself as an arsenical compound 

 out of ores very poor in this element, everywhere where arsenic 

 is present in any quantity, as, for instance, in the magnetic 

 pyrites of Wiersberg in Oberfranken, as I have already shown, 

 where it forms cobaltous mispickel. 



Olivine or chrysolite is a very basic compound (R: Si=2 : 1); 

 but neutral silicates also contain heavy metals, and most pro- 

 minently hornblende and augite. 



Next in regard to hornblende, of which I have tested several 

 varieties for heavy metals. By testing samples of 20 — 40 grammes 

 each — I found along with very much iron : 



