^^rMPsoN — -C())ifrihtiiioiis in 'Minrralor/ii of W.A. 
()5 
enveloped by a sinRb* cr\-stal individiuil of kyanite, whose con- 
timiitv over llie whole "eye” can l)e Ira.ced by reflection from a 
cleavage face. 
(.“)) Sittitrolilr. ('nil alia. 
In 1920, in descril)ing staurolite from Mogaimber, the writer 
referred to specimen.s of tlie mineral liaving reached Perth from 
an indefinite loca1it>^ alioni la miles N.l',. of (dngin.* Wattle 
Flat, referred to above is 12 miles N.la. of Gingin, and at this 
point ]\lr. de Gonrey C'larke and the writer discovered a loose 
boulder of staurolite schist early in 1926. A turther search by 
Mr, Bowley and myself resulted in (be discovery of the outcrop 
of this rock witb'u a few yards oi the kyanite schist described 
above. 
The staurolite schist occurs on the crest of a ridge on the west 
side of Wattle Flat close to the north end of f.oc, 805. It forms 
an approximately vertical band se\'eral leet wide in a series of 
gneisses and schists, including gneissic microcline-hornblende 
granite, ((uartz-kyanite-biotite schist, (|uartz-garnet-biotite gneiss 
and gneissic. epidiorite. d'he staurolite rock ai)pears at first sight 
to be a highly ferromagnesian rock, the coni])arativcly large 
flakes of black biotitc envelojiing and concealing all the other 
constituents except the large “eyes” of staurolite. A section of 
the rock, however, reveals its constituents in approximate order 
of abundance to be (1) c|nart/,, (2) staurolite, (3) biolite, (4) horn- 
blende, (5) muscovite, (6) chlorite, (7) fels])ar, (8) iron ore, (9) 
zircon. There is no indication of the rpiartz ever having been 
water worn. 
A partial analysis shows that the fresh rock as a whole 
carries 73 per cent, of silica, and 13 per cent, of alumina. These 
arc the proportions present in typical Darling Range granite, e.g., 
at Mahogany Creek {'SiO;., 73; Al/):f, 14), and Bannister 
fSiOo, 72; Al-..0;i, 12.5). The iron in the staurolite schist appears, 
however, to be higher and the lime lower than in these granites. 
The only other staurolite schists whose analyses are on record 
differ greatly from this in their low silica ])ercentages, 40.8 in one 
from Mogumber analysed b}^ the author, and 41.5 in one from 
Switzerland cpioted by Grubenmanii.t 
Idle staurolite occurs as abundant “eyes” in the schist, which 
are very prominent on exposed surfaces, and round which the 
scales of biotite and muscovite sweep in graceful curves. Fach 
“eye,” measuring from 5 to 30 mm., is usually conpiosed of a 
single crystal individual which, however, is very rarely solid 
*Jour. Roy. Soc. W.A., Vol. VTL, p. 71. 
tSince this paper was read Prof. E. W. Skeats has drawn my 
attention to the analysis of a staurolite schist from Kanton 
Tessin, Switzerland, showing Si02, 66.97; AI 2 O 3 , 14.22. 
