The
Chines Gold-field, as examined for this report, includes an area 14
miles long in a nortli and south direction, by a width of about 6
miles. Practically all mining in this region is in the hands of a few
needy fossickers, in shallow works, and these miners work on suffrage,
miles of the main belt of lode formations being held by non-working
leaseholders. The Climes field has, of course, had its part of the
State's great mass of sedimentary rock-layers (slate and sandstone)
crumpled, corrugated, and cracked with the rest of the mass, and during
the progress of this movement the rock-beds took the form of arches and
troughs, whose strikes are pretty well identical with those of the
general corrugations of the rock-beds.
Five
miles to the west of the Climes main belt of lode formations is the
crest of a mass of granite known as the Mount Beckworth Range, and 5
miles to the east of the main belt of lodes another mass of so-called
granite runs almost parallel to the Mount Beckworth Range, and maybe
seen in the workings of the Spring Hill and Central Leads alluvial
mine, near Clementston. The relative positions of these two elevations
of granite to each other, in my opinion, governed the arrangement of
the systems of cracking in the sedimentary rock-layers, which their
upward movement had apparently corrugated. These layers, although
originally 5 miles, perhaps, in thickness, are probably no more to the
earth's thickness than is the thickness of a man's shirt to the width
of his body from shoulder to shoulder, and the cracking therein extends
only to depths above which the rock-beds are cool enough to crack. Now,
in certain lengths of country containing systems of cracks or fractures
there has been north and south pressure applied, due to. a rising or
falling of the whole area of certain lengths of country, resulting in a
multiplicity of fracture lines. Such regions present features of
structural arrangement of the lines of fracture wider as a system, and
wider in parts in the individual lines. These wide parts have been
centres of concentrated circulation. Their more open lines of fracture
receive more fluid than do the less open parts of the lines of
fracture, and this fluid containing in solution quartz for the most
part, greater facility is afforded for the concentration and the
precipitation in them of the metals in solution also.
Thus,
we have long lines of golden quartz known as " shoots," tadpole-shaped
formations of golden quartz, V-shaped formations of golden quartz,
known as "jewellers' shops," and flat vein formations of golden quartz
known as " indicator patches." The deposition of gold in all these
varieties may be in nuggets or comparatively fine particles, in
accordance with the more or less horizontal or vertical line of the
drainage passage itself, or of a floor of obstruction to it. Thus, the
nearer the line of passage to the vertical the less nuggety the gold,
and the more nearly horizontal the line of the passage, the more
nuggety the gold (see Figs. Nos. 1 and 2). Obstruction to circulation
appears to be essential to the precipitation of payable deposits of
metals. A comparative stagnation to circulation in situations where
[Report sent in 23rd October, 1902.]
