THE GEOLOGY OF MITTAGONG. 341 
V. CHEMICO-MINERALOGICAL CLASSIFICATION. 
As the authors place great value on a new system of 
rock classification recently propounded by U.S.A. petro- 
graphers,’ it is proposed to adopt their methods in classify- 
TABLE OF ANALYSES. 
I iE III IV V VI 
> A eee 66°68 55°86 55°16 46°22 43°31 39°91 
A ee 14°63 15°25 16°67 9°33 16°68 13°67 
EN) 2 Ue 2°18 4°92 2°36 5°85 al 6°55 
2) oo 2°31 6:07 hal 7°39 9:00 8°98 
2 30 -20 56 3:08 | 10°58 | 11:96 
eee 1°88 2713 2°30 10°80 7°95 6:18 
_ 0 EO Ses Bee 6°12 234>) 95:65 3°21 2°94, 1:28 
Coo ee 4°02 9°28 6:97 - 1°80 97 66 
H.O (100° C.) 38 ‘70 85 94, 88 3°66 
H.O (+100°C.)| —--83 50 ‘88 2°30 1:72 3°74 
Be ai as "05 1°80 1°50 4°46 08 “40 
Ss Se See eee -20 "65 “60 3°70 2°20 1°75 
0 2 ee trace ee ie pa aS ae 
isle a 28 16 38 “80 65 ‘61 
ee ee. trace trace 5 32 05 trace 
ete Pees. 2 3. ‘03 |minute trace] faint trace 03 "02 02 
*§S (soluble) ...... "05 "09 "02 10 trace ‘20 
Lot Le nil nil nil 02 ‘11 ‘21 
Lis) 7 Pe ee ate ous trace trace 
J A eee 49 "42 AT 32 43 18 
li | ae nil trace trace "24 trace nil 
pee nes) 5. nil nil nil trace nil nil 
Li) 2 es oe trace trace trace nil nil nil 
Oe ed ee nil nil nil 02 trace trace 
100°43 | 100°42 | 100°08 | 100-41 99°81 99°96 
"02 03 "07 "05 10 
a) ae 100°41 100°39 100°01 100°36 99°81 99°86 
= Ly ee 2°618 2°706 2675 2-801 2°995 2°891 
Legend. 
I. Trachyte from the trigonometrical station on top of Mount Jellore. 
If. Melanocratic Gib syenite from Loveridge’s Quarry. 
III. Leucocratic Gib syenite from Saunder’s Quarry. 
IV. Essexite from Jellore Creek near the junction with Powell’s Creek. 
V. Basalt from the capping on “ Woodlands.”’ 
V1. Picrite from Jellore Creek, half mile up from junction with Powell’s _ 
Creek. 
* Cross, Iddings, Pirrson—Washington. “ Quantitative classification 
of igneous rocks.” 
* This represents both sulphides and soluble sulphates; and as pyrites 
can be distinguished in most of the specimens, this sulphur has been cal- 
culated as sulphide. 
