66 
Stmpson" — Co)itrilnitio}is to ]\[ineralogy of W.A, 
staurolitc. Commonly it is an intcrgrowth in almost any propor- 
tion.s of staurolitc and granular quartz, tlie former mineral im- 
])ressing a Fontainebleau structure on the eye. As much as 70 
or 80 per cent, of quartz may Im thus enveloped, though usually 
not more than 30 or 40. The colour of tlie eye varies with the 
proportion of c|uartz, usually it ranges from chesnut brown to 
tawny (Ridgway ll'm to 13h). A typical light brown “eye” which 
was sectioned was found to consist of about 46 or 47 per cent. 
stauroUte. and the same of (piartz, whilst the balance was made 
up of granular iron ore, muscovite, biotite, and chlorite, with 
pleocliroic haloes in the last, surrounding some small and some 
relatively large zircon crystals. In only one instance were crystal 
faces indistinctlv seen, though the strong cleavage parallel to (010) 
is readily observed in most cases. 
Genesis of the Chiltcrmfi Kyanite and. StmiroUie. 
Too little is known of the petrology and structural geology of 
tlie Chittcring Valley to be sure of the origin of the staurolitc and 
kyanite observed there. Tt is to be noted in this connection that 
the staurolitc rock at Wattle Flat occurs in at least one, possibly 
three, narrow bands, interbedded with garnetiferous gneiss and 
more normal gneiss, as well as with a siliceous kyanite schist. A 
microline granite only slightly gneissic is found within at most a 
few miles on two sides of the Wattle Flat occurrence, and within 
at most a mile of the South Bindoon and Lower Chittcring 
kyanite localities. Innumerable other rock outcrops are to be 
seen in every direction in this hilly country, but as yet have not 
been examined. 
Tt would appear as if the whole of this area were occupied by 
a fluxion gneiss traversed by occasional epidiorite dykes, and that 
either certain portions were originally more highly foliated and 
showed greater differentiation on a small scale, due to a local 
rekuive poverty in alkalis and lime, or that shearing stresses have 
spent themselves on certain zones, without affecting the whole 
mass, and along these zones there has been a circulation of heated 
waters cliarged with active chemical agents. The latter theory 
would explain the presence of numerous lenticular quartz veins at 
all three localities, as well as the development of kyanite crystals 
in the heart of a quartz vein at T.ower niittcrlng. The produc- 
tion of secondary mica from felspar involves the solution and 
removal of two-thirds of the potash and silica in the original 
mineral. Were this common process intensified and part of the 
remaining alkali removed, kyanite or one of its congeners would 
be likely to result, and might be crystallised in part in situ, in part 
in cavities with the dissolved silica, resulting in a kyanite-bearing 
quartz vein. 
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