THE SCHISTOSE ISLES. 



of chlorite schist or of hornblende schist, unless some 

 mineralogist shall think it necessary to contrive new terms 

 for them. 



1 . Chlorite schist, black mica, and felspar. 



2. Hornblende, mica, and felspar. 



3. Hornblende, chlorite, quartz, and green compact 

 felspar. 



The last which I shall enumerate are more ambiguous 

 in their aspect than remarkable for their ingredients ; the 

 ambiguity being produced by the predominance of that 

 which is on other occasions the least prominent ingre- 

 dient, namely felspar. 



1 . A rock consisting of felspar of a texture intermediate 

 between the granular and confusedly crystallized, or else 

 of common compact felspar, interspersed with crystals of 

 dark green or blackish hornblende, the whole mass being 

 of a pale grey colour. It is at times schistose, at others 

 it merely divides into thin beds, and subsequently by cross 

 fractures into irregular prisms. 



This rock ought not perhaps to be considered a subor- 

 dinate variety ; since it occurs in the several parts of 

 the districts under review, in great abundance. It is also 

 found occupying an extensive tract in the islands Luing, 

 Torsa, and Seil, where it was formerly mentioned. In 

 these, it has been shown to alternate with chloritic and 

 micaceous schist, and with quartz rock; on the main- 

 land it occurs with these rocks and with common horn- 

 blende schist; its boundaries being always distinctly 

 marked, and the alternations taking place without gra- 

 dation. 



2. A rock with the general aspect and structure of the 

 large grained granitic gneiss, but consisting of chlorite 

 schist and felspar only; the latter forming distinct but 

 imperfectly crystallized grains, very predominant, and 

 only separated from each other by thin laminse of the 

 former. This rock is not strictly schistose, but breaks 



