The form is a
cube modified to an octahedron and a rhombic dodecahedron. These rich
finds are usually the produce of pockets or 'jewellers' shops.' I am not
aware if there be any truth in the rule generally accepted: 'The forms of
gold are found to differ according to the nature of the underlying rock:
if it is slate the grains are cubical; if granite they are flat plates and
scales.'
And, lastly, the sluice begat the jet, or hydraulicking proper, which is
at present the highest effort of placer-mining. We thus reverse the
primitive process which carried the wash-dirt to the water; we now carry
the water to the wash-dirt. In California I found the miners washing down
loose sandstones and hillocks of clay, passing the stuff through sluices,
and making money when the gold averaged only 9_d_. and even 4_d_. to the
ton. A man could work under favourable circumstances twenty to thirty tons
a day. An Australian company, mentioned by Mr. R. Brough Smyth, with 200
inches of water, directed by ten hands, 'hydraulicked' in six days 224,000
cubic feet of dirt. The results greatly vary; in some places a man will
remove 200 cubic yards a day, and in others only 50.
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