5. The quartz being in crystalline condition is not a sign of its containing no gold. See No. 12.
6. The visibility of gold is worth nil for Nos. I, 5 aQd
8, are rich in gold. It has recently been stated that assayers are of
no use. We are told we must be able to see and judge by the eye as to
whether a quartz reef •will pay and that it is a poor tale to have it
tested. However such statements are not worth much. If we see the gold
and know that it extends in the quartz, we then know without assay that
it will pay and its extraction may be at once begun with.
Assaying
of fair samples is very necessary. There is not sufficient
sight-evidence in many varieties of quartz to warrant gold being there
in paying quantity. Even the rough amalgamation process, so commonly
used by the miner is unreliable where the gold occurs with pyrites. Nor
can the amalgamation process be successfully used for its extraction in
such cases, e. g., three samples of auriferous pyrites were operated upon not long ago.
(a) From Siberia which contained 100 grams to the ton. (4) „ Venezuela ,, 300 „
(c) „ California „ 150 „
The
first yielded all its gold by amalgamation. The two others, both in the
raw state and after roasting, yielded only insignificant quantities.
From further experiment, it was inferred that the presence of antimony
and arsenic prevent amalgamation.
The
tailings of old^ines are now being re-worked by the " Chlorine process
" or by the still better method devised by Mr. W. A. Dixon. See "
Directions for extracting gold, silver, and other metals from
pyrites." Proceedings of tlu Royal Society, vol. 20.
Ceylon quartz is rather too glossy in appearance and from many localities is destitute of metal of
any kind, or having caverns either empty or filled with earthy matter.
The pyrites are of too brassy a nature. However, we have quartz
partaking of the character of Nos. 6 and 16 in Hewaheta and Ramboda. A
somewhat similar quartz to 10 and 15 occurs in Balangoda and the
district around.
In
the Nawalapitiya district, we have a quartz partaking of the nature of
II, 12, 13, but no metal is visible. The mineral galena, mispickel and
blende have not been recorded up to the present time as occurring in
this island.
Mr.
Dixon, we know, has judged rightly in stating that the mere colour of
quartz is no certain criterion of its value. We took with us to
Melbourne a specimen of gold-bearing quartz from the Alpha Mine in
Southern India, and, judging by what we had seen in Devalah, we
expected to find the specimens of Australian gold-bearing quartz sent
to the Melbourne Exhibition full of pyrites and rusty coloured. Some
such quartz we did find exhibited, but the leading specimens (some of
them immense blocks) were pure white, shading away to grey). A person
acquainted with only the surface quartz of Devalah would certainly
never have suspected the existence of gold in pure white and
occasionally crystalline quartz. The uneducated eye, therefore, is
here at fault, but the merest tyro soon learns the value of " Black
Jack," or blende as an indication of the presence of gold, equally
with mundic (iron or arsenical pyrites) and galena. Blende, Mr. Dixon
explains, is a sulphide of zinc, while galena is composed mainly of
sulphide of lead; sometimes rich in sulphide of silver. We suspect that
neither " black Jack" nor galena exist in Ceylon, any more than the
special " Lower Silurian" slate formations so strongly insisted on in
Victoria. But " mispickel," which Mr. Dixon describes as arsenical iron
pyrites, ought surely to exist. The first great revolution in the
search for gold was the discovery that hundreds and even thousands of
feet below the alluvials of Mount Alexander, Bendigo, Ballarat,
Arrarat, and other once rich but entirely or partially exhausted gold
fields, and underlying enormous masses of the basaltic rock known
locally as " blue stone," vast stores of the precious metal lay hidden.
It is found either in situ in the old quartz and slate formations, or
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