VOLCANIC ROCKS.—CASE IV. — Sy 
VOLCANIC ROCKS. 
Case IV. 
OLDER VOLCANIC. 
1, BAsaur. List No. R i 
East of East Creek, Western Port. 
Black, dense and compact: contains 
a few embedded, crystalline grains of 
olivine and of a mineral with a bright 
bronzy lustre on the surface of cleavage. 
2. BASALT. List No. R f, 
West Head, east side, Western Port. 
Greenish-black ; it seems to be an 
intimate mixture of felspar, augite and 
olivine. 
3. BASALT. 
North Melbourne, + sheet 1 N.W. 
Greenish-black, very dense and close- 
grained: contains olivine in crystalline 
grains; suitable for road metal, 
4. DECOMPOSED BASALT., 
Bruthen Creek, Gippsland. 
An earthy mass of mottled appear- 
ance. Surface stained and coated with 
oxide of iron. 
5. NODULE IN BASALT. 
King street, Melbourne. 1 sheet 
1 S.E. 
Illustrates the concretionary form of 
decomposition which takes place in 
basalt and other igneous rocks. 
6. Brown Iron-Ore (Hydrous 
Sesqui-oxide of Iron). 
North Melbourne. 4 sheet 1 N.W. 
Associated with, and doubtless chiefly 
derived from, the iron constituents of 
the older basalt during decomposition. 
7. Brown Iron-ORE. 
Same locality. 
Very similar to No. 6. 
8, EARTHY HEMATITE. 
Same locality, 
More oxidized than Nos. 6 and 7. 
Portion of a nodule in basalt. 
! 
9. DecomroseD BASALT. 
Deep Creek, Hurdy-gurdy. 
Very friable and incoherent; almost 
pisolitic, from the abundance of small 
ironstone nodules. 
10. DecomroseD BASALT. 
Flemington. } sheet 1 N.W. 
Has become a clay, but still exhibits 
the concretionary structure indicative 
of decomposition. 
. 11. DECOMPOSED BASALT. 
12. DECOMPOSED BASALT. 
Raleigh's Punt, Saltwater River. 
4 sheet 1 N.W. 
Has a thick, ferruginous, mammil- 
lated coating. Is rapidly passing into a 
brown, homogeneous clay. 
‘18. DECOMPOSED BASALT. 
_ Same locality as last. 
Is also quickly passing into a clay; 
though not quite so much decomposed 
as No, 12. 
14, DECOMPOSED BASALT. 
Deep Creek, Hurdy-gurdy. 
Of an olive-green color, when freshly 
broken, passing into. a homogeneous 
clay. 
15. DecomposeD BASALT. 
Forming a red, brown, and white 
mottled clay. 
16. Rep Cray (Earthy). 
Map No. R 11. 
Section 7, Bolinda. } sheet 7 N.E. 
Associated with, if not actually re- 
sulting from, the decomposition of 
basalt in situ, and underlying the newer 
basalt, 
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