80 VICTORIAN MINERALS—CASE XIV. 
remarkable instance of an obsidian ball. 
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 244 :— 



Spec. 21, Spec. 24, Spec. 24a, 
sp. gr. 2°47, sp. gr. 2°41, 8p. gT. 2°36. 
Silica at .. 73°70 eee 72°23 con 68°45 
Sesqui-oxide ofiron ... 6°08 ae 2:28 ise 7:21 
Alumina ft S «499 a 16:43. on , 5'88 
Lime oth an fi) at 3:17 jE 8'11 
Magnesia ns an WD 2:12 5 1°03 
Protoxide of manganese — Peroxide of manganese 0°50 
Titanic acid ... YE _ “6% — or H 
Soda... "ri mt tet) ‘ 36 
Potassa aes an uE pee pf ih tees 7 
Loss by ignition do hik aT 0:13 — 
99°65 101°01 98°34 
28. OBSIDIAN. 25. OLIVINE. 
Broadford, (?) Mount Franklin. 4 sheet 15 S.E. 
24, OBSIDIAN. 
Geelong District, 
List No. Md 18. 
24a. BLUE OBSIDIAN. 
Geelong. 
Green, granular, or sub-crystalline 
masses, occurring in the scoriaceous 
basalt of this extinct crater. 
26. OLIVINE. 
Mount Franklin. 4 sheet 15 S.E. 
A reddish and green, sub-crystalline 
mass in vesicular grey basalt. 
WNote.—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, 
Hell’s Corner, Back Creek, Bayn- 
ton. } 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. s 
29. TOURMALINE. 
Dandenong. 
Black water-worn pebbles. 
Note.—Tourmaline (schorl) 
‘ 
80. ScHorL, Map No. Mu 15, 
Near the Brewery, Maldon, 
4 sheet 14 N.W. 
Radiating crystals in granite. 
81. ScHort. Map No. Ra 52, 
Specimen Gully, Barker’s Creek. 
4 sheet 14 §,E, 
Stellar tufts on the faces of joints in 
altered sandstone, at the junction of the 
granite and slate rocks, 
31a. SCHORL. 
A water-worn crystal. 
is of very frequent occurrence, but 
almost entirely confined to the plutonic and metamorphic older rocks, 
