SO see 
remarkable instance of an obsidian ball. 
VICTORIAN MINERALS—CASE XIV. 
From its low specific gravity, 
1:06 (being only half that of the buttons, 2:47—Specimen No. 21), it 
was deemed advisable to have it cut. 
The following are the results of analyses, by 
a beautiful polish. 
It now shows a cavity, having 
Mr, J. Cosmo Newbery, of specimens 21, 24 and 24a :— 
Spec. 21, 
a sp. gr. 2°47. 
Silica sx: +» 73°70 
Sesqui-oxide of iron 6'08 
Alumina fE s.. 499 
Lime ewe yE ZDI) 
Magnesia n ar 0710 
Protoxide of manganese — 
Titanic acid... T — 
Soda... ben se 520 
Potassa “°C coe | 4835 
Loss by ignition ees) OtH5 
99°65 
23. OBSIDIAN. 
Broadford. (2?) 
24. OBSIDIAN. 
Geelong District. 
List No, Md 18. 
244. BLUE OBSIDIAN. 
Geelong. 

Spec. 24, Spec. 24A, 
sp. gr. 2°41. Sp. gr, 2°36, 
1 72°23 xt) 68°45 
oy: 2:28 7'21 
16°43 tee 5°38 
3:17 Bae 8'11 
fi 2'12 1°03 
an Peroxide of manganese 0°50 
Wes — 35 0°30 
eee 4°65 7°36 
Tor 013 — 
10101 98°34 

25. OLIVINE. 
Mount Franklin. sheet 15 S E. 
Green, granular, or sub-crystalline 
masses, occurring in the scoriaceous 
basalt of this extinct crater. 
26. OLIVINE. 
Mount Franklin, 4sheet 15 S.E. 
A reddish and green, sub-crystalline 
mass in vesicular grey basalt. 
Note.—Olivine occurs in all the newer basalts (except where they 
appear as true dolerites), especially round points of eruption, and may 
be regarded as an essential ingredient of these rocks. 
It varies in size 
from small grains to masses 12 to18 inches in diameter. No crystals 
have hitherto been discovered. 
27. TOURMALINE (Schorl). 
Map No. M 25. 
Hells Corner, Bach Creek, Bayn- 
ton. 4 sheet 51 S.W. 
Occurs in the surface drift at the 
- junction of the granite and Silurian 
rocks, and is derived from the granite. 
28. TOURMALINE CRYSTALS. 
Map No, M 25. 
Same locality as last. 
These crystals exhibit the terminal 
planes. 
29. TOURMALINE. 
Dandenong. 
Black water-worn pebbles. 
30. SCHORL. Map No. Mu 15. 
Near the Brewery, Maldon, 
i sheet 14 N.W. 
Radiating crystals in granite. 
31. SCHORL. Map No. Ra 52. 
Specimen Gully, Barker’s Creek. 
4 sheet 14 S,E. 
Stellar tufts on the faces of joints in 
altered sandstone, at the junction of the 
granite and slate rocks, 
381A. ScHoRL. 
A water-worn crystal. 
WNote.—Tourmaline (schorl) is of very frequent occurrence, but 
almost entirely confined to the plutonic and metamorphic older rocks, 
