134 
r. R. Le Mesurieh. 
Extinction is ditiicuJt to ascertain owing to the sheaf-liko form and 
extroino fineness of (lie fibres, Imt appears to be straight or of small amount. 
N in all directions is greater than that of metliylene iodide (1-74), and bire- 
fringence moderate. 
J’leocliroisni is strong from honey yellow to deep amber. 
4’he material is readily soluble in acids and is decomposed by 5 *^'0 NaOH 
solution, in the latter case about 90 % of the is soluble. 
An analysis of the crushed matei'ial separat(Kl by floating in methylene 
iodide Sp. gr. 3*005, and sinking in bromoform Sp. gr. 2*85, then air dried and 
driefl to constant weight over HoSO^ and barium perchlorate gave the following 
results : — 
— 
Mols. 
Mol. ratio. 
f SiO ^ 
1*88 
insol. in HCl 
\Xot"SiO, 
. *03 
^AUO. 
•43 
FOgO:i 
54*11 
338S 
3*4 
MnO 
Nil 
CaO 
Nil 
Sol, in HCl 
MgO 
Nil 
NaoO 
•58 
KA) 
■12 
.PM, 
27*24 
1919 
2 
H.O 1- 
15*60 
8659 
8*6 
SO;: 
Nil 
Cl 
Nil 
99*99 
The excess mols. of F'e20;j and H^O over the ratio 3:2:8 may bo 
accounted for by intergrown limonite which it was impossible to eliminate. 
SUMMARY. 
A physical and chemical description is given of the mineral boraunite, 
a hydrous xdiosphato not jn’eviously reported from this State. 
(1) UeoL Surv. W,A. Bitll. 20, pp. 14-23. 
(2) Jour. Roij. Boo, W.A., 1932, XIX, pp. 13-16. 
