!31 
The interior of the nodules is of an almost uniform bright 
canary yellow colour, the exterior is disguised somewhat by 
a brownish or reddish coating, covering a thin slightly bleached 
zone of mineral The chief characteristics have been determined 
on material from the surface of which about two or three milli- 
metres had been removed. The interior of the nodules thus 
prepared was found in thin slice under the microscope to be 
homogeneous except for some streakiness of colour ,due probably 
to slightly different degrees of hydration or to slight staining m 
places with ferric hydrate. A few minute specks of tantalite 
were thus seen embedded in the mineral and a little colourless 
mineral which appeared to be an altered felspar. The mineral 
is opaque in layers thicker than one-fifth of a millimetre. Colour, 
canary yellow’ Brittle, earthy, amorphous. Hardness, 2.5 to 
3. Specific gravity, 4.4 to 4.7. Strongly radioactive. Com- 
position, hydrated silicate of lead, uranium, and thorium, the 
analysis of a well scraped fragment weighing 6 grammes yielded 
the results given in column x below. 
I 
I. 
Pilbarite. 
Wodgina 
n. 
Thorogum- 
mite. 
Texas. 
III. 
Mackin- 
toshite. 
Texas. 
IV 
Urn no* 
phane. 
(Uranium 
ochre). 
Saxony 
V. 
Urano- 
thorite.* 
New York 
State. 
Uranium trioxide, U0 3 
27.09 
22.43 
22.404 
62.84 
9.96 
Thoria, ThO, 
31-34 
4x44 
l 45-30 
52.07 
Ceria, Ce 2 0 3 
.19 
1 6.69 j 
Yttria, Y 2 0 3 
•49 
1 
1.80 
Alumina, Al 2 0, 
■ 15 
.96 
. . . 
trace 
•33 
Ferric oxide, Fe 2 0 3 ■ - 
.20 
.85 
§ I - 15 
2.88 
4.01 
Lead oxide, PbO 
17.26 
2.16 
3-74 
40 
Lime, CaO 
■57 
.41 
•59 
5-49 
2-34 
Magnesia, MgO 
.21 
.10 
.04 
Manganese oxide, MnO 
trace 
. . . 
Potash, K 2 0 
.09 
• • • 
42 
. . . 
1 - 11 
Soda, Na 2 0 
.04 
. . . 
.68 
Silica, Si0 2 
12.72 
13.08 
13.90 
14.48 
19-38 
Phosphoric oxide, P 2 0 5 
x.08 
1. 19 
■67 
O O 
. . . 
Tantalic oxide, fa 0, 
■47 
.OO 
* ‘ * 
* * * 
Water above ioo°, H 2 0 
4.16 
7.88 
4-31 
1 13-79 
l n -30 
Water at ioo°, H 2 0 . . 
3-50 
1.23 
•50 
( 
J 
Helium, He 
trace 
* * * 
* * * 
99.56 
98.32 
96.50 
99.48 
99-95 
Sp.gr 
4.68 
4-50 
5-44 
3-86 
4 -i 3 
* Uranium— bearing variety of thorite 
f U0 2 § FeO 
