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Australian Diamonds. 99
miles
distant. The drift has lost its basaltic capping, which has been
removed by denudation, and the drift itself has probably been
re-distributed. Captain Charles Rogers, the proprietor, estimated that
the wash-dirt would yield about 30 carats of Diamond to thé load of 27
cubic feet. Mr. G. A. Lawson, during a visit to the mine, obtained 122
Diamonds from one barrow-load of the drift, and 146 from a second
barrow-load ; as it takes ten barrows to form a "load," the richness of
the deposit is very remarkable. The Rev. Milne Curran states that while
he was visiting the mine, 29 small Diamonds were washed out of a
hundred-weight of the drift. He calculated, from an examination of
several parcels, that about 12 per cent, of the Diamonds are really
good stones, 45 per cent, are marketable, and 20 per cent, more may be
worth cutting, whilst the remaining 23 per cent, are useless as gems.
Of
late years considerable attention has been given to the Diamond-bearing
drifts in the tin-mining districts near Inverell, not far from the
junction of Cope's Creek with the Gwydir River. The field known as
Boggy Camp is situated about 12 mites south-west of Inverell, in the
parish of Mayo, County of Hardinge. The tin-drifts, which consist of
deposits of sand and gravel, placed between floors of basalt above and
a granitic bed-rock below, contain not only Diamonds, Gold and
Tin-stone, but such minerals as Sapphire, Zircon, Tourmaline, Garnet
and Topaz. The famous claim known as " The Star of the South," is
situated on a hill of basalt, in which shafts have been sunk to the
underlying drift, and levels have been systematically driven to open up
the wash-dirt. In the course of eighteen months upwards of 3,000
Diamonds were found. Mr. E. F. Pittman, the Government Geologist of New
South Wales, stated in his official Report for 1895, that when he
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