1853.] Report on tlie Geological Structure of the Salt Mange, 257 



beds of a coarse silicions sinter containing in some places particles 

 of chalcedony are of frequent occurrence. Throughout the shales 

 selenite or transparent gypsum may be noticed in laminae and crys- 

 tals, and in small impure concretions of radiating crystals, associated 

 with similar nodular concretions of impure sulphate of barytes and 

 argillaceous haematite. These along with the silicious sinter, have 

 probably been deposited by thermal waters penetrating the shales, 

 the variegated colours of which, may probably result from their having 

 been exposed to different degrees of heat during the prevalence of 

 thermal action. Such coloured clays are, we believe, of frequent oc- 

 currence in countries where thermal action is prevalent. 



On tracing the shales upwards they gradually become arenaceous 

 and acquire a greenish colour. A few dark shales then follow and 

 mark the transition into the formation which succeeds. 



Copper Ore. 



The existence of copper ore in the Salt Range was first made 

 public by Capt. Hollings, Deputy Commissioner of Le'ia. It occurs 

 chiefly in the form of nodular concretions, varying in size from a 

 millet seed to that of a walnut, disseminated through the variegated 

 shales and clays resulting from their disintegration, on the surface of 

 which, particularly after rain, their green colour brings them promi- 

 nently into view. Small green patches of silicate and carbonate 

 of copper may also be observed in masses of the silicious sinter, 

 which we before mentioned as occurring in the shales. The origin 

 of this concretion is most obscure, but it is probable that the parti- 

 cles of copper in solution in thermal waters were diffused through 

 the shales, and that by a process of crystallization they have aggre- 

 gated into the form we now find them. Their resemblance to the 

 nodular concretions of kunkur found every where in the desert 

 alluvial soil throughout the Punjab, induces us to believe that they 

 were formed in a similar way. So complete, however, has been the 

 separation of the particles of copper from the shales in which they 

 are found, that not a trace of copper can be detected in them on 

 submitting small portions to chemical analysis. 



The nodules of copper ore are occasionally very pure, but fre- 

 quently it forms only the centre of the nodular concretionary masses 

 of sulphate of lime and barytes, which we have above alluded to. 



