16 J. A. PHILLIPS ON CONCEETIONAUT PATCHES AND 



are remarkable for the number and variety of the dark- coloured 

 inclusions they contain, and they consequently afford unusual facilities 

 for the study of such bodies. 



The Newry granite is essentially composed of quartz, orthoclase, 

 and black mica, and is usually made up of small and somewhat im- 

 perfect crystalline grains. It is, however, sometimes coarser in 

 texture, and occasionally becomes porphyritic by enclosing fragments 

 of felspar imbedded in a fine-grained ground-mass of a bluish-grey 

 colour. 



ISTear the Goragh-Wood railway-station granite is exposed for a 

 length of over 400 yards and to a maximum height of above 20 

 yards. The rock is here principally of the description locally known 

 as *' white granite ;" but close to the station it becomes porphyritic 

 for a width of about 35 yards, and this " blue granite" is extensively 

 quarried for ornamental purposes. It exhibits some slight indica- 

 tions of foliation, and its colour is due to the presence of numerous 

 minute scales of black mica disseminated through the mass ; the 

 imperfect crystals of felspar, porphyriticaUy enclosed, rarely exceed 

 the dimensions of a small bean. 



Immediately opposite the railway-platform the porphyritic granite 

 terminates abruptly against beds of a fine-grained schistose rock, 

 tilted at a high angle ; this rock, which is above 60 feet in width, 

 separates the blue granite from the ordinary white variety. 



The granites of Newry, or Slieve Croob, are regarded by Prof. 

 Hull * as being of metamorphic origin ; and Mr. F. W. Egan, author 

 of the memoir explanatory of the geological map of this portion of 

 Ireland, believes them to be derived from Silurian rocks by transition 

 through mica-schist and gneiss f. Mr. Kinahan, on the other hand, 

 classes them with eruptive granites and describes the blue granite 

 of Goragh Wood as an elvan which has come up through the Newry 

 granite and must consequently be of more recent date J. 



Examined under the microscope this granite is seen to be 

 composed of quartz, orthoclase, a felspar exhibiting cross stria- 

 tion, a very few small crystals of a distinctly triclinic felspar, a 

 dark or black mica, green hornblende, sphene, a few needles of 

 apatite, with occasionally magnetite, pyrites, and perhaps a little 

 rutile. A specimen of the schistose rock taken near the centre of 

 the band against which the blue granite abuts, and consequently 

 about 30 feet distant from the granite on either side, was found to 

 be a fine-grained mica-schist. It is composed of finely granular 

 quartz, occasional fragments of felspar, numerous minute nearly 

 colourless garnets, small flakes of mica, usually of a dark colour, 

 a little green hornblende, and a few spots of magnetite and 

 pyrites. 



A specimen of the same schistose rock obtained from its immediate 

 junction with the blue granite is rather coarser in texture and is 



* Building and Ornamental Stones of Great Britain &c., p. 45, note. 

 t Explanatory Memoir to accompany sheet 59 of the maps of the Geological 

 Survey of Ireland, p. 12. 



J ' Geology of Ireland,' pp. 209, 210. 



