the degradation of the older strata. According to Daintree, [a) no
auriferous vein of any kind has been found in any Secondary or Tertiary
strata, or in the igneous rocks erupted through any such newer
formations; and as a result of his experience, the same observer gives
the following as the modes of occurrence of gold in Australia:—(I) In
pyritic diorites and felstones in Queensland, and their alluvial
drifts; (2) in pyritic granites in New South Wales; (3) in drifts from
auriferous serpentine in Queensland, also in the two northern colonies;
(4) in more or less reqular veins with quartz and calcspar in the
preceeding rocks; (5) in quartz and other veins in Devonian and Upper
Silurian strata in proximity to similar igneous rocks, which is the
general character of the Victoria quartz veins; (6) in veins of
mctamorphic rocks of unknown age in Queensland; and (7) in quartz veins
in Lower Silurian strata, without any apparent connexion with igneous
masses. The latter occur only in Victoria, and are of comparatively
minor importance. In the northern territory of South Australia,
alluvial gold mining has recently been developed to a considerable
extent in the neighbourhood of Port Darwin in the Gulf of Carpentaria,
the export being from 2,000 to 3,000 oz. monthly.
Statistics.—There
are no means of stating exactly the total gold produce of the world for
any particular year, as in many of the larger producing countries no
systematic returns are obtained, and in others where such returns arc
collected, their publication is often delayed for a considerable time.
The following figures, mostly derived from a recent statistical woik, A
Soelbeer, Edelmetall-Produktion, 1879, with some additions from
late official sources, will give some idea of the relative importance
of the different countries. Previous to 1837 the first place was held
by Russia, and the estimated average annual yield from all sources was
in the decennial period 1841-50, 1,760,500 ounces.
The contributions of the different countries are as follows :—
