323 



represented and the quartz is sometimes seen to be idiomorphic with 

 respect to it; a somewhat unusual feature. A rock from Stony Tarn, 

 collected by Mr. WARD, illustrates the fact that felspar may play the 

 role of matrix to quartz in a very perfect manner. 



The so-called " syenite " of Ennerdale is a fine-grained pink rock 

 mainly composed of quartz and felspar intergrown as in the grano- 

 phyres. The ferro-magnesian constituent is feebly represented by green 

 chloritic aggregates. Iron-ores are also very feebly represented. This 

 rock bears a close relation to the granophyres of Mull and Skye. If 

 the term syenite be used in WERNER'S sense it is inapplicable to this 

 rock as quartz enters largely into its composition. There are no decided 

 porphyritic crystals; but the orthoclase which is intergrown with quartz 

 to form what may be termed the ground-mass is often in optical 

 continuity with large patches which have more or less the aspect of 

 porphyritic constituents, as if a considerable amount of felspar substance 

 had first separated as distinct crystals and then the remainder of the 

 felspar substance had intercrystallized with quartz to form the matrix. 



I. II. III. 



Si0 2 . v 75-223 ... 73-573 ... 71'442 



ALA .* 11-140 ... 13-750 ... 15-340 



FeA tr - -615 1>23 



FeO ... 1-771 ... 2-103 ... 1-107 



CaO ... 1'624 ... 1-064 ... 1-064 



MgO ... 1-081 ... -396 .. -720 



K 2 ... 4-516 ... 3-512 ... 4-439 



Na 2 ... 3-996 ... 4'315 ... 3*951 



P 2 5 ... -149 ... -012 ... -118 



C0 2 ... tr. ... tr. ... tr. 



Loss -500 -660 -589 



100-000 100-000 100-000 



I. Skiddaw granite. 

 II. Eskdale granite ; S. of Great How. 

 III. Ennerdale granophyre, from Scale Force, near Buttermere. ( J ) 



Cheviot District. Granitic rocks occur in the central portions of 

 the Cheviot District, about Staindrop Rigg and Hedgehope. The minerals 

 which enter into their composition are orthoclase, plagioclase, quartz, 

 dark mica, augite (malacolite, ROSENBUSCH), iron ores and apatite. 

 The augite is nearly colourless in thin section and similar in character 

 to that of the augite-granitites of the Vosges and the augite-syenites 

 of Monzoni. There is a considerable amount of variability in the 

 relative proportions of the different constituents. Sometimes, as in the 

 neighbourhood of Linhope Spout, the ferro-magnesian constituents are 

 sufficiently numerous to give a dark syenitic or dioritic aspect to the 

 rocks. As a rule, however, they have the aspect of a pink or grey 

 granite of medium grain. Veins of eurite or felsite in which the 



(1) The analyses are quoted from Mr. WAKE'S Memoir already referred to. 



