24 
Felspaihic 
PLUTONIC ROCKS, 
- 60 
Granite 
Quartz 
Felspar 
Mica — white 
or black ... 
28 
53 
19 
to 80 
per 
Silica . . . 
72 
Alumina 
15 
Potash ... 
5 
Soda ... 
3 
Iron, &c. 
5 
cent, of Silica. 
Varieties of Felspar. 
Orthoclase — with Potash — - 
oblique system — S.E. of 
Ireland. 
Aibite-with. <SWtf,-anorthic 
— Mourne Mountains. 
Oligoclase, — withPotash and 
Soda, — anorthic — Scandi- 
Aplite— Quartz and Felspar. 
Eurite or Whitestone— the same — fine grain. 
Elvanite — Quartz and Felspar, in veins as if from Granite. 
C p_i of A „ 0 f compact Felspar — 80 per cent. Silica — in dykes — sometimes 
J?eiStOne \ porphyritic, 
1 Claystone— Earthy ditto, ditto. 
I Pitchstone— glassy. 
Porphyry — rock with crystals. 
Mornhlendic and Augitic — 45 to 55 per cent, of Silica. 
(Quartz. 
Felspar. 
Hornblende. 
Silica 
Magnesia 
Lime 
Alumina 
Protox. Iron 
Fluoric Acid . 
46 
19 
14 
12 
7 
1.5 
„ , ( Felspar (sometimes Albite.) 
Greenstone { Hornblende. 
! Silica ... ... 54 
Ox. Iron ... 25 
Magnesia ... 14 
Lime and Alumina 4 
Diallage 
Silica 
Magnesia 
Lime 
Prot. Iron 
^ Alumina 
(Silica 
Magnesia ... 
Water 
Diorite — Albite and Hornblende 
Silica 
Alumina 
Lime 
Potash and Soda 
Magnesia 
Iron and Manganese 
Diabase— Greenstone with Augite. 
Aphanite— the same— close grain. 
53—50 
15—17 
19—16 
9—12 
2— 3 
Melaphyre 
... 44 
... 43 
... 13 
(Corsican Granite.) 
52 
22 
6 
6 
4 
9 
