On the Mineralogy of Dublin and Wicklow. 187 
The quantity of silica required to saturate 140°72 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 cent. 
Orthoclase, : : A 15°44 2 
Albite, . ; 2 22°10 i 
Margarodite, A ; - L52'6 sa 
Lepidomelane . ° ° 5:81 
Paste (silicate of lime) . : 4:92 
100-00 
(B) The accidental Minerals found occasionally in the Dublin 
and Wicklow Granites are :— 
Beryl, « 5 ° 
Spodwmene, « . 
Kiltlinite* (altered 
Spodumene). 
Schorl, . ° ° 
Garnet, ° . 
Flworspar,  . . 
Apatite, ° ° 
A galmatolite, ° 
Pale, greenish, opaque crystals. 
Loc. Dalkey, Killiney, Glenmalure, Gleumacanas, 
Long, bent, greenish grey prisms. 
Loe. ”Killiney. 
Fibrolamellar, light green to brownish yellow, 
brittle ; sp. gr. 2°56. 
Loe. Killiney. 
Black. 
Loc. Clarinda Park, Kingstown; Dalkey, Three 
Rock Mountain, Stillorgan, Roundwood: Glen- 
malure, Poulmounty. 
Small red and brilliant crystals. 
Loc. Dalkey, Killiney. 
Cinnamon colour. 
Loc. Glenmalure, Kilranelagh. 
Small cubes. 
Loc. Golden Bridge. 
Octohedra, lining cavities. 
Loc. Dalkey Island, Dalkey Quarry. 
Light green, translucent, hexagonal prisms, with 
lateral edges replaced. 
Loc. Three Rock Mountain, Killiney Hill. 
Loc. Dundrum, Luganure. 
2. THe MINERALS OF THE METAMORPHIC SLATES OF DUBLIN 
AND WICKLOW.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. 
+ 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. 
