1815.] On the Old Silver Mine in Linlithgowshire. 121 



deeply covered with soil. The heaps of ruhbish in the neighbour- 

 hood of the mine are now our surest guides, and in them the fol- 

 lowing minerals may be observed : — 



I . Heavy Spar. — Tliis appears to have occurred in great quantity 

 in the vein, and may even lie observed filling up some small rents 

 in the adjacent rocks. It is usually of a reddish colour, sometimes 

 white, and presents the following sub-species. Heavy spar earthy 

 found as a coating to the cavities of the other sub-species. Granular 

 heavy spar is very abundant, and in some specimens appears to pass 

 into compact heavy spar. Curved lamellar heavy spar is in small 

 quantity at the old workings, but occurs abundantly in the cross vein 

 mentioned as opening into the lime-stone quarry. Straight lamellar 

 heavy spar appears in greatest plenty, usually compact, sometimes 

 crystallized in the form of a rectangular four-sided table, having all 

 the terminal planes levelled. In these sub-species of heavy spar the 

 ores of the following metals occur either imbedded or disseminated. 



2. Lead. — Lead glance was the ore sought after, and yielded so 

 considerable a proportion oi silver as to bear the expense of extrac- 

 tion. All the pieces of tliis ore which I have seen are broad 

 foliated. 



3. Nickel. — Both the ores of this metal are to be found here, but 

 in small quantity. The copper nickel is in roundish pieces, from tiie 

 size of a pea to that of a pigeon's eg^. The nickel ochre sometimes 

 occurs as a coating to the preceding species, and likewise fills small 

 cells in the heavy spar, where it appears to hold the rank of an 

 original deposition. 



4. Cobalt. — I have not observed any of the alloys or oxides of 

 this metal ; but tlie arseniate of cobalt, or cobalt crust, fills the 

 cavities of the heavy spar, and is spread as a coating on its surface. 



5. Zinc. — The only ore of this metal which is here observable is 

 a small portion of brown blende. The same ore associated with lead 

 glance. Iron pyrites, brown spar, and lime-spar, may be observed 

 in many of the small veins which traverse the strata of lime-stone 

 ill this district. 



Amidst the rubbish may also be observed masses of calcareous 

 sand-stone and induratccl clay. After heavy rains, when fresh 

 portions of the rubbith have been exposed, the poultry which feed 

 near the place are observed to sicken and die. Are we to consider 

 tiie cobalt crust as the cause of the mischief? 



The rarest ores enumerated above are those of nickel and cobalt. 

 1 hrse have been found in otiicr places of Scotland, but not situated 

 in the same kind of rocks. Some time ago I observed among the 

 manuscripts of tiie late Dr. Walker, Professor of Natural History 

 in the University of lidinburgh, a short notice of his having between 

 the years 17(jI and i7(>* found copj;er nickel and nickel odne in 

 the njines at Lead llilis and Wanlockhead. These mines are 

 situated in transition rocks. Hence we nnist consider nickel as 

 iHflonging not only to x\\v primitive class of rocks, but to the tran- 

 sition, and even to a new member of the lloctz class. 



