Kinahan — On Granite and Met amorphic Rocks. 177 



finely worked on any face, are of fair scantlings, and are capable 

 of long and heavy bearings. Many of them split readily into 

 .good durable paving-setts of suitable sizes. The stones in dykes 

 and intrudes invariably split better than those in contemporaneous 

 beds. 



The metamorphosed whinstones, the " hornblende rocks" of 

 Macculloch, are more or less granitoid. They can be raised in 

 massive blocks very suitable for coarse work, such as piers, sea- 

 walls, &c. Of late, ophytic varieties have been introduced into 

 the London market, under the trade name of "green granite." 

 These are principally from Sweden and Norway. But more 

 recently, Mr. Flynu, of the Bessbrook Granite Company, has been 

 manufacturing a green stone obtained at Rostrevor, Co. Down ; 

 while Mr. Parnell has exhibited a very handsome mottled stone 

 from Arklow rock, Co. Wicklow. 



The different varieties of hornblende and allied rocks are not 

 uncommon in West Galway (Connemara) ; while they have been 

 also recorded from places in Mayo, Donegal, Tyrone (near Pome- 

 roy), Down, Armagh, Louth, Wicklow, Wexford, and elsewhere. 



[The granitoid (or granite-like) hornblende rocks often partake', more or less, of 

 the nature of ophyte (serpentine) ; some, indeed, being highly crystalline ophytes. 

 This class of rock is usually found in tracts of highly metamorphic rock, such as those 

 of Galway, Donegal, and Tyrone ; but sometimes they occur elsewhere. In the me- 

 tamorphic regions, where ophytes occiu - , there are also usually in connexion with them, 

 or as independent masses, ophytic hornblende rocks of a granitoid aspect, like the 

 Swedish rocks. Up to the present time no special attention has been called to 

 these, and only rarely have they been recorded ; but wherever ophytes occur, it 

 is highly probable that they also will be found. Further on, in the different Terri- 

 torial Descriptions, the places where they are known to exist, or are likely to be 

 ■discovered, will be mentioned. At present, however, as no quarries have been opened, 

 nor trials made, it cannot be said if they can be procured of suitable dimensions. A 

 very necessary qualification is that they be free from iron, as otherwise they are liable 

 to discolouration and weathering.] 



In the mechanically formed adjuncts of the volcanic rocks, 

 such as the agglomerates and tuffs, there are some good building- 

 stones suitable for cut-stone purposes. Many of them have already 

 been described among the calcareous rocks and the sandstones ; 

 but they will again be referred to in their different localities. 



Some felstones, whinstones, and tuffs have been changed into 

 ophytes (serpentine) and steatytes (soapstone) ; they, with the allied 

 camstones (Pyrophyllytc), have already been described in my 



