9.—REPORT ON THE ROOKS OF THE MOUNT WILLIAM 
GOLD-FIELD. 
(By A. W. Howitt , F.G.S.) 
The following thin slices were submitted to me by Mr. H. Herman, 
B.C.E., the Acting Government Geologist, with the request that I would 
furnish some account of them, which I have now much pleasure in doing :— 
No. 445 
„ 446 
„ 447 
V 
55 
55 
448 
449 
450 
55 
452 
55 
453 
454 
„ 455 
55 
456 
55 
464 
From block 89a, parish of Nekeeya, county Ripon. 
From block 89c, parish of Nekeeya, county Ripon. 
From Neild’s Creek, immediately north of block 91a, parish 
of Nekee} r a. 
From block 82, parish of Nekeeya. 
From block 82, parish of Nekeeya. 
About one and a half miles west of Greene's Gap, parish of Jalur, 
county Dundas. 
About one mile west of Greene’s Gap, parish of Jalur, county 
Dundas. 
About three-quarters of a mile west of Greene’s Gap, parish 
of Jalur, county Dundas. 
Wannon Valley, about two miles east of Wannon River, on track 
from Mount William to Victoria Valley. 
From Swan’s paddock, block 77, parish of Nekeeya, county 
Ripon. 
At junction of the Grampian sandstones with diorite, block 82b, 
parish of Nekeeya, county Ripon, 
At contact of dyke with the Grampian sandstones, Newton and 
King’s claim, about three-quarters of a mile east of the Wannon 
River, parish of Nekeeya, county Ripon. 
Dyke, up to two feet in width, in quartz-mica-diorite. 
After examining these slices I found that Nos. 445, 450, and 464 
were best adapted for my purpose, as fairly representing the igneous rocks 
of the collection, and being also less altered by decomposition than the 
other samples. 
Nos. 455 and 456 represent the sedimentary rocks of this series. 
No. 445. 
This is macroscopically a medium-grained liolocrystalline rock, composed 
of grey to whitish coloured triclinic felspars, with biotite mica and quartz. 
Occasional felspar phenocrysts are evident. 
The thin slice shows that in addition to the above-mentioned minerals 
there are also magnetite and hornblende. 
The biotite is in ragged-ended crystals which, where least altered, are 
pleochroic in shades of dark-brown to brownish-yellow. As is commonly 
the case in rocks of this character, the mica has been more or less bleached, 
and in places converted into a green chlorite. In certain instances this is 
in concentric radial forms, the component fibres of which are optically 
negative. 
