205 
Australia, and in the interior of Australia. It will be a matter of extreme 
interest to keep a chart of all the localities in which these 'bodies are found, 
arid also as to their abundance over certain tracts. Every scrap of infor¬ 
mation on these matters should be recorded. 
Mr. D. J. Mahony, M.Sc., has examined a thin slice of one of the bombs, 
and found it to be an isotropic glass with no trace of the formation of 
crystals. 
The following report has. been made by Mr. P. G. W. Bayly, who 
made a chemical examination at the departmental laboratory of some ob¬ 
sidian buttons from Coolgardie presented by Mr. Ward, Assistant Govern¬ 
ment Geologist of Tasmania: — 
The sample consisted of six small obsidian bombs of the typical shape 
as found in Australia—button and mushroom shape. 
Before crushing, the bombs were scrubbed with dilute hydrochloric 
acid to remove the ferruginous clay which tilled the srrtall pinhole depres¬ 
sions on the surface. 
ANALYSES. 
A. 
B. 
C. 
Si 0 2 ... 
70-62 
69-80 
75-46 
ALOg ... 
13-48 
15-02 
11-27 
Fe> 0 3 ... 
0-85 
0-40 
1-17 
FeO 
4-44 
4-65 
2-05 
MgO 
2-42 
2-47 
0-27 
CaO 
3-09 
3-20 
0-53 
Na 2 0 .. 
1-27 
T 29 
3-45 
k 2 o 
0-99 
—; -j.; 
2-56 
4-88 
H 2 () +(above 110C) 
0-01 
not estd. 
0-28 
H 2 O-( 110 °C) 
0-06 
not estd. 
0-07 
co 2 
nil 
— 
nil 
Ti 0 2 . 
0-90 
0-80 
0-50 
PM) r 
nil 
nil 
nil 
so 3 . 
trace 
? 
trace 
Cl 
trace 
trace 
MnO 
0.42 
0-18 
trace 
NiO 
trace 
% 
— 
CoO 
trace 
— 
— 
LUO 
trace (strong) 
good trace 
trace (spectroscopic) 
SrO . ... 
— 
nil 
— 
BaO 
— 
<) 
— 
- 
. 99-78 
100-37 
99-93 
Specific Gravity ... 2.454 2-454 (grey) 2 353 
(greenish) 2-405 
A. Obsidian buttons from Coolgardie, West Australia, collected by Mr. Ward, and 
analyzed by Mr. P. (4 W. Bayly. 
B A small button from the Upper Weld, Tasmania, collected by W. H. Twelve- 
trees, Esq., Government Geologist of Tasmania, and analyzed by Dr. Hillebrand, of the 
U.S.A Geological Survey. See Report of the Secretary for Mines (Tasmania) for the 
year 1905. 
C. bsidian from the volcanic formation at Hauraki Gulf, New Zealand. Collected 
by Mr. E. J Dunn, and analyzed by Mr. P. G. W. Bayly. Inserted for comparison 
with the analyses of the obsidian buttons. 
