648 REPORT — 1901. 



this into solution— probably in the form of carbonate— from which solution 

 any one of various reagents, "in most cases probably decomposing organic matter, 

 has reduced the dissolved substance to the metallic state. In this form it has 

 been deposited as thin sheets along the divisional planes of the rocks situated at a 

 lower level than its point of origin. In the form of films of this kind it occurs at 

 Boyleston, in Renfrewshire, where it is found in lavas of Lower Carboniferous 

 ap-e; and at Ballocbmyle, in the joints traversing the marls of the New Red 

 Iloc'ks there. I may remark, in passing, that these rocks so closely resemble the 

 Bunter Sandstone that I should never have hesitated to refer them to that horizon 

 had not a different opinion regarding their age been expressed by the distinguished 

 author of ' The Scenery of Scotland.' 



Native Copper also occurs in the form of minute particles — possibly crystals — 

 in some of the Prehnites of Boyleston and Glen Farg. Doubtless these varieties 

 of Prehnite owe their colouring matter to the presence of this mineral, just as 

 the ordinary green variety of Prehnite owes its colour to diffused compounds of 

 copper of other kinds — possibly to Chrysocolla. The same metal also occurs at 

 Boylestone, disseminated throughout some of the beautiful crystals of Calcite 

 which line some of the drusy cavities of the lavas there. When Native Copper is 

 enclosed in these crystals the external form is much more complex than where the 

 metal is absent. 



Some Chalcopyrites must undoubtedly be classed amongst ebb-products also, 

 seeing that a second generation of crystals often occurs upon minerals whose 

 secondary origin cannot be doubted. Atacamite has been claimed as a Scottish 

 mineral, but, it seems to me, on insufficient grounds. 



(224) Cuprite, as might be expected, occurs in connection with the other 

 decomposition products of copper ores. Usually it occurs as one of the consti- 

 tuents in the compound known as Tile Ore ; but occasionally, as at Glen Farg, it 

 shows traces of crystalline exterior ; or as at Boyleston, where Mr. Craig-Christie 

 has got it in the capillary or velvet-like form. Some of the silicate of copper from 

 Lauchentyre appears to me to be coloured red by Cuprite, which may also occur 

 there in the free state. 



(2.30) Tenorite has not yet been proved to occur as a separate Scottish 

 mineral ; hut the black Chrysocolla from Lauchentyre and other mines in the 

 neighbourhood may possibly owe its coloration to this mineral. 



(288) Malachite calls for no special remark here beyond the statement that it 

 does not appsar to show crystalline termination at any locality in Scotland except 

 at Sandlodge, in Shetland, where it seems to have been taken for Brochantite. 



(289) Azurite is singularly rare in Scotland, and has not yet been found with 

 visible crystalline faces. (290) Aurichalcite, (741) Linarite, and (739) Caledonite, 

 well known as secondary products of the decomposition of veins containing Copper, 

 do not call for any special remark in this abstract. 



2. A Revised List of the Minerals known to occur in Scotland. 

 By J. G. GooDCHiLD. 



The following list embraces the whole of the minerals whose claim to rank as 

 good species and whose occurrence in Scotland seem to the author to be beyond 

 doubt. The list will probably have to be extended : — 



