Kinahan — On Granite and Metamorphic Rocks. 223 



In the west of the county, near Clifden, and thereabouts, there are 

 granitones, probably of Silurian age. These are very suitable for 

 harbour and cut-stone purposes, as they rise in squarish blocks of 

 fair scantling, tool, and plug easily, and are apparently durable ; 

 although they do not retain their light-greenish colour. 



At Waterloo Bridge, a little eastward of Clifden, a quarry was 

 opened when the quay at that place was being built ; and very good 

 stones, suitable for cut-stone purposes, were procured. This rock 

 is somewhat allied to granitone. It cuts and polishes well ; it is 

 of a mottled leek-green colour. 



Elsewhere no quarries have been opened ; except small ones for 

 quite local use. The granitones, allied to hornblende-rock, and 

 possibly suitable for ornamental purposes, are given on page 224. 



The elvans, in connexion with the Corvockbrack granite, have 

 already been mentioned. One of the associated felstones is partly 

 decomposed into kaolin. 



The Felstones vary from fine and compact to granular and por- 

 phyritic ; some are very silicious {felsytes) ; others very felspathic. 

 In colour they are of various shades of grey, blue, purple, green, 

 and white. They are not in much, if any, request. Those near 

 Roundstone, margining Gralway Bay, have already been mentioned. 

 In N. W. Mayo they are not very numerous. There is an exposure 

 of them with dykes on Clare Island, Clew Bay ; as also some dykes 

 N.W. of Nephin, and others along the north coast, (g. s. m.) 



In the metamorphosed Ordovician and Arenig (?) rocks are dykes 

 of euryte, with their associated granitic roots at Lugnanoon. These 

 seem to be of Silurian age, as they run into the interbedded sheets 

 [Bundorragha euryte) that extend from the Atlantic eastward to 

 Loughs Mask and Corrib. They are of various shades of purple 

 and green, and some of them are nice-looking stones, and polish 

 well, and might be used for ornamental purposes, especially those 

 near Lough-na-fooey, where they are variegated and streaked. 

 They do not seem to have been utilized for building purposes ; 

 good stone being so easily procured everywhere. 



The ivhinstones are most varied in age and character. All the in- 

 trudes, dykes, and sheets associated with the Ordovicians, Arenigs and 

 Cambrians (?) are changed into varieties of hornblendyte, hornblen- 

 dic gneiss, and hornblende-rock ; those least altered being pyroxenic- 

 hornblendic. In the Silurians of Galway there are beds and 



