On the Mineralogy of Dublin and Wicklov;. 187 



The quantity of silica required to saturate 14072 parts of lime 

 is about 351-8 ; from which we infer that the paste amounts to 

 4.92 per-cent. of the rock. 



The mean composition of the Leinster Granite is, therefore, as 

 follows : — 



Quartz, 



• 



• 



• 



32-57 



per c< 



Orthoclase, 



• 



• 



• 



15-44 



>> 



Albite, 



• 



• 



• 



22-10 



jj 



Margarodite, 



, 



■ 



• 



19-16 



jj 



Lepidomelane 



• 



• 



• 



5-81 



n 



Paste (silicate of 



lime) 



• 



• 



4-92 



v> 



100-00 



(B) The accidental Minerals found occasionally in the Dublin 

 and VVicklo w Granites are : — 



Beryl, . . • Pale, greenish, opaque crystals. 



Loc. Dalkey, Killiney, Glenmalure^ Glenraacanas. 

 Spodumem, . • Long, bent, greenish grey prisms. 



Loc. Killiney. 

 Killinite* (altered Fibrolamellar, light green to brownish yellow, 

 Spodumene). brittle; sp. gr. 2-56. 



Loc. Killiney. 

 Schorl, , . , Black. 



Loc. Clarinda Park, Kingstown; Dalkey, Three 

 Rock Mountain, Stillorgan, Round wood, Glen- 

 malure, Poulmounty. 

 Garnet, . . Small red and brilliant crystals. 



Loc. Dalkey, Killiney. 



Cinnamon colour. 



Loc. Glenmalure, Kilranelagh. 

 Fluorspar, . . Small cubes. 



Loc. Golden Bridge. 



Octohedra, lining cavities. 



Loc. Dalkey Island, Dalkey Quarry. 

 Apatite, • • Light green, translucent, hexagonal prisms, with 



lateral edges replaced; 



Loc. Three Rock Mountain, Killiney Hill. 

 Agalmatolite, • Loc. Dundrum, Luganure. 



2. The Minerals of the Metamorphic Slates gf Dublin 



AND WlCKLOW.t 



In addition to the Micas and Hornblende forming constituent 



* The so-called Killinite is an altered spodumene, from which the lithia has been 

 washed out by weathering. 



f The absence of Garnet, Idocrase, and other lime minerals from the metamorphic slates 

 of Leinster is remarkable and very different from what is observed in Donegal and 

 elsewhere. 



