412 SKY. MINERALS. 



prehnite, the same mineral is intermixed throughout 

 so as to form an integral part of the rock, often 

 passing into mesotype, as it appears to do in other 

 more decided instances. It has been said by Haiiy that 

 prehnite has not been found forming an integrant part 

 of rocks ; but as a compound of a similar nature occurs 

 in the Kilpatrick hills near Glasgow, an exception must 

 be made in favour of these instances. I may here add, 

 that a corresponding rock may be seen on the opposite 

 coast of Rasay. 



It is perhaps superfluous to say that nodules of 

 chalcedony, often hollow and containing crystallized 

 quartz, are occasionally found in the trap rocks of 

 Sky, since they are of such common occurrence in this 

 substance. They must nevertheless be considered rare 

 here, and it is more rare to find them solid like those 

 so common in Scotland. The only specimens I found 

 were near Loch Brittle, and these were of a dull grey 

 colour, zoned, but presenting little variety. The quartz 

 sometimes forms nodules without the investing; crust of 



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chalcedony, and the cavities are sometimes, in addition, 

 sprinkled with crystals of stilbite, of analcirne, and of 

 chabasite. 



Of those mineral substances which are the least frequent 

 in trap rocks, steatite occurs in considerable quantity; 

 it is tender, and always of a greenish dirty hue. It is 

 sometimes found in very small nodules ; but in other 

 places, as near Dunvegan and in the parish of Kilmuir, 

 it is so abundant as to have been dug with the intention 

 of exporting it for economical purposes. 



I have already mentioned that epidote is found both 

 in the clinkstone and in the trap, but in too small 

 quantities to render any further account of it necessary. 

 It is thus far worthy of notice, as it is one of the few 

 minerals which seems to appertain to rocks of very 

 different characters and periods of formation. I ought 



