21 
2,4iOO oz. ; in, 1880,* reef gold 442 oz., alluvial 615 oz. ; in 1881,* estimated total 
3.000 oz. ; in 1882,* estimated total 3,000 oz. ; in 1883,* reef gold 200 oz., alluvial 
1.000 oz.; in 1884,* estimated total 1,911 oz. ; in 1885,* estimated total 1,000 oz. ; in 
1886,* estimated total 500 oz. ; in 1887,* roof gold 937 oz., alluvial 121 oz. ; in 1888,* 
estimated total 328 oz. ; in 1889,* reef gold 613 oz., alluvial 1,058 oz. ; and in 1890, f 
estimated total 2,020 oz. 
_ The Charters Towers Field stands first among A.ustr.xlian gold-producing areas, 
will he seen that the above returns from the Cape are so small as scarcely to aifect 
e totals credited to Charters Towers. 
TIio richest part of the goldfield lies on the western edge of a large area of 
t,ranitic rock. The granite varies from a type in which orthoclase felspar, mica, and 
huartz are the essential minerals, and hornblende an occasional or accidental mineral, to 
ypo ni which, in addition to the constant orthoclase and quartz, honihlondo is the 
^sential and mica the occasional mineral, llefcrence may be made to Mr. A. AF. 
iir e s Micro-Petrographical Notes. {See post.) 
West of the granite several reefs are worked in less highly metamorphosed rocks, 
u not only are these reefs less rich in gold, but the gold is also more alloyed with silver. 
^ ese locks consist of quartzites, greywackes (of mixed quartz, felspar, and hornblende 
mica), shales, and slates. The slates and shales are highly iinpreg- 
Da e with iron peroxide. The stratified rocks strike as a rule N.AV. and S.E., and 
ip at over 45° to N.E. and S.AV. They afford no direct evidence of their age, but are 
overe unconformably by the Middle Devonian Limestone of Burdekin Downs. 
The reefs in the central portion of the field have no uniform trend, but they 
ave invariably an underlie to the north side of their outcrop, and generally at a 
comparatively low angle. 
Down to the water-level the gold was “ free ” in a ganguo of granitic debris and 
^uar z, mixed with “ brownstone ” or decomposed pyrites. Below that level the gold 
hi quartz associated with a “ mundic ” composed of pyrites, galena, and zinc- 
6U e, which has not proved hard to treat. 
mi . . '^*'0 gi’oatest depth at which gold has yet been worked is 1,500 feet (vortical), 
nis IS in the Mills United Mine. 
ve' "^^out sixteen miles south of Charters Towers gold occurs in thready hematite 
balTh ^ ’’oticulate through a volcanic “ Neck,” named Mount Leyshon. This neck 
pierced partly through greywackes and slates, and partly through a porphyry, 
fel^ is composed of straw-coloured silicated felspar, witli crystals of orthoclase 
send,''^^ quartz, the latter occurring, however, most frequently in rounded blebs. It 
uecurs^t fbrongh tlic greywackes and slates, and also tlirough the granite which 
fillecl'** ° north. The Neck is the once deep-seated pipe or core of a volcano, 
mat fragmental material which supplied the ashy outbursts. This 
foi considerably in texture, some portions being merely aggregations of fine 
fel^pathic dust, while others 
porphyry^ cemented to 
are agglomerates of 
coarse angular debris of broken 
matrix of dint felted with iron oxide. 
retbor by a sparse 
^ ■'=11 crystals am' 
per h^^^^ lu.aterial is exactly such a.s could bo manufactured from the waste of tlio 
that^^ of felspar in some cases appear to have been developed in the asli 
the 
Passintr through 
ken Crystals and rounded blebs of quartz are scattered tlu’ougbout the matrix; in 
le nii ■ ■ - - 
.‘■y- 
that Put for the granular and elastic appearance of the matrix, the resemblance to 
^c.iaceut porphyry rocks would he comjrleto. 'fhe rock has for some lime paid for 
linn n -r " stamps as a whole, picking the auriferous veins being an 
— Pussi ility. Now and then larger masses of auriferous stone are met with. In the 
Rands, loc, cit., p. 18. 
t Warden’s Report for 1890. 
