THE SHAP GRANITE AND ASSOCEATKD ROCKS. 283 



to show the dying-out of apophyses of the porphyritic granite of 

 Kostreuen, which seems to have many analogies with the Shap Fell 

 rock. 



Any ideas based on the general appearance of this rock are, how- 

 ever, dispelled by a closer scrutiny, which proves that the whole is 

 granite, and the semblance of a contact quite illusory. The granite 

 differs somewhat from the normal type, especially in possessing a 

 general " parallel structure." This parallelism is shown not only in 

 the banding of the rock and the imitation of intrusive tongues, but 

 also in the orientation of the large felspars and their restriction, 

 for the most part, to particular lines. The pinkish colour of the 

 rock along these lines, must be referred to subsequent chemical 

 action, as in the case of the pink granite in the quarries ; and it 

 here follows fine cracks which have probably served as channels for 

 infiltration. 



Slides of the rock [1071, 1280, 1281] show some curious cha- 

 racters. There is a distinct banded structure on a small scale. In 

 some bands quartz is abundant, and then tends to be idiomorphic 

 towards the felspar as in the normal granite : in other bands felspar 

 is far in excess of quartz, and is then moulded by it, as in the dark 

 patches in the quarries described above. Another link with these 

 dark patches is the abundance of magnetite and apatite, but we have 

 not identified any sphene. The rock, moreover, has peculiarities 

 not found in either the normal granite or the dark patches. The 

 magnetite, mainly occurring in streaks parallel to the banding, shows 

 some crystal forms, but in some cases moulds the felspar. The 

 brown mica is partly of early consolidation, but partly posterior to 

 the felspars. Much of this mineral shows green coloration or 

 bleaching, and finally conversion into a yellowish-brown substance 

 with complete loss of the original structure. 



The most striking feature, however, is the abundant occurrence of 

 andalusite in idiomorphic, though rather rounded, prismatic crystals, 

 usually coated with little flakes of yellowish or greenish-brown mica 

 (see PI. XI. fig. 3). The andalusite is usually clear and colourless, 

 only occasionally showing the characteristic pleochroism : 



o (c), pale rose-pink ; (3 and y, colourless or very faint green. 



The inclusions are of magnetite, zircon, and mica, and around 

 some of these, especially the zircon, the well-known pleochroic halo* 

 is well seen, the colours being : 



a (c), bright yellow ; /3 and y, colourless. 



Andalusite as a regular constituent of granite has been recorded 

 by Mr. Teallt and Dr. E. Cohen t of Greifswald. As an accessory 

 in granitic dykes it is also recorded in Spain §, Cornwall, and 



* Eosenbuscb, ' Mikr. Pliysiogr. d. petr. wicbtig. Miner.' 2nd ed. (1885) 

 p. 380. 



t Min. Mag. vol. vii. (1887) p. 161. 

 X Neues Jahrb. (1887) vol. ii. p. 178. 



§ Macpherson, Ann. Soe. Esp. Hist. Nat. vol. viii. (1879) p. 229. 



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