00 
Rtmpron — Confrihuiions to Alineralogy of W.A. 
natural mineral, bnt upon artificial molybdic oxide, with which it 
was for long- quite erroneously assumed to be identical. 
As first noted by A. (libl) Maitland and the aiitlior in 1917*, 
excellent specimens of this mineral in a great state of purity have 
been found from time to time in tlie upper workings on the 
molybdenite deposits of Mt. Mulgine (Lat 29°S., Long. 117°E.'). The 
mineral occurs in joints or small cavities in granite greisen or 
pegmatite, in some cases being plainly pscudomorphous after 
mol 3 ’l)denite. The masses are all distinctly fibrous, even when 
still preserving the broad foliation of the original molybdenite. 
'I'hey are very friable, and therefore difficult to collect and 
handle, passing soon into a michoscopically fibrous powder, the 
individual fibres having a diameter of 2 to 8 microns with lengths 
up to 1 mm. 
As some doubt has existed regarding the composition of the 
minerpil, more particularly in regard to its water content, an 
analysis was made of carefully selected material taken from the 
largest single mass obtained, which weighed nearly 2 grammes. 
A very small quantity of associated (piartz was removed with 
methylene iodide, and after thorough washing in the cold with 
xylol, alcohol and ether in succession, it was kept under loose 
cover sufficiently long to be sure of its having reached equilibrium 
under prevailing cool dry atmospheric conditions. Analyses were 
made of two separate lots at intervals of some days, the results 
being as follow: — 
Fern 
hnolyhditc, 
Afulginc. 
Lot 
A 
B 
Theory 
per 
mols. 
per 
mols. 
(Simpson) 
cent. 
cent. 
per cent. 
Ferric oxide, 
Fe.O. . . . . 
17 87 
112 
18.29 
115 
17.44 
iMolybdic oxide, 
MoOx 
. . 62.90 
437 
(62.46) 
434 
62.90 
Water over CaCl 
1. 10.20 
566 
1 19.25 
1069 
9.83 
Water at 250° 
, . 9.95 
552 
J 
9.83 
100.92 
100.00 
100.00 
The appreciable difference in water percentage between the 
two analyses of the one well-mixed mass of material, as -well as 
the variable and often quite low proportions of water noted by 
Schaller and othersf were explained by experiments made to 
determine the temperature and rate at which the mineral loses 
*A.R.G.SAV.A., 1916, p. 10, 25. 
tU.S.G.S. Bull. 490, pp. 84-92. 
