Investigation of Some Phosphatic Nodules from Dandaragan, 79 
Western Australia. 
No attempt was made to differentiate between the magnetite-hematite 
and the limonite which in most specimens are in the ratio of between 1 : 2 
and 1:3. In calculating the relative weights the following specific gravities 
were used; quartz 2-65, collophanite 2-7, glauconite 2*6, iron ores 4-5, 
felspar 2*55. Phosphatised wood fragments were included with the matrix 
when measuring the collophanite content. Felspar was estimated as micro- 
cline. The accessory minerals were neglected. 
From Table 1 it can be seen that the relative proportions of the three 
main constituents quartz, collophanite and glauconite vary considerably 
between wide limits, though quartz and collophanite appear to occur in inverse 
ratio one with the other. The fact that the total glauconite, iron ore and 
felspar content is appreciable in all specimens examined, indicates that notable 
amounts of iron oxide and alumina are present in the nodules. 
In Column 4 of Table 1 is given the average composition of nodules A, 
B, and C from Cook’s Deposit. Then assuming the following approximate 
compositions for the minerals ; glauconite Si0 2 52%, Fe 2 0 3 20%, Ai 2 0 3 10%, 
MgO 3% (1) and K 2 0 3% (2) ; iron ore Fe 2 0 3 85% ; and felspar Si0 2 65%, 
A1 2 0 3 18%, K 2 0 16% (3) ; the Cook’s Deposit nodules have the approximate 
partial chemical composition shown in Column 1 of Table II. 
No attempt has been made to estimate the CaO and P 2 0 5 content, etc., 
as the exact composition of collophanite (essentially hydrous calcium phos- 
phate with variable amounts of calcium carbonate, fluoride and sulphate, 
etc.), is not known. 
The above figures bear interesting comparison with the results of a com- 
plete chemical analysis of a composite sample of nodules from Cook s Deposit 
made at the Government Chemical Laboratory shown in Column 2 of the 
following table : — 
1. 
Table II. 
ANALYSIS OF NODULES. 
1. 
2. 
Si0 2 
0 / 
Jo 
40-6 
0 / 
JO 
46-02 
A! 2 0 3 .... 
1-8 
2-36 
Fe 2 0 3 
7-1 
3-38 
MnO .... 
0-02 
MgO 
0-36 
0-42 
CaO .... 
23-62 
K 2 0 .... 
0-85 
0-80 
P 2 0 5 .... 
16-66 
co 2 
1-70 
IU) : 
1-29 
Ho() - 
0-98 
S0 3 (water soluble) 
0-04 
S0 3 (acid soluble) 
0 • 15 
ci .... .... 
0-01 
F 
Present 
Loss on Ignition 
0-41 
98-09 
Micrometric analysis snuwnig paumi , T / „ Lr-r x 
Cook’s Deposit. All percentages shown are by weight. (Anal. K. R. Miles). 
Chemical Analysis of a composite sample of nodules from Cook’s Deposit. (Anal. 
H. P. Rowledge). 
