MINERAL ANALYSIS
TO THE EDITOR.
SIR, - From the favourable reception which was accorded a recent lecture
on gold, it is evident that there is a general desire for that class of
information which would enable any person travelling through country
supposed to contain valuable minerals to perform a qualitative analysis of
any mineral that had a likely look about it, and it sems to me, that what
is wanted is a preactical dissertation, either by lecture or written
articles, that would give the information necessary to render pospectors a
little less "practical" in the sense used by the lecturer.
It is not possible, in article, to give the details that might be shown
with the aided diagrams, such as the formation of the country where
different minerals might be expected, and the appearance of true and false
indications of the precious metals, but perhaps it might be useful in some
degree if a short account were given of the way in which tests my [sic] be
made for half-a-dozen of the principal metals, in a manner that is easy
and cheap, and it is the more necessary as there seems to be a tendency to
consider gold the only thing worth seeking, Tuesday the experience of
several places in the other colonies, where fortunes have been unwittingly
thrown aside to be picked up by the first comer, who has the wits to try
for other metals than the one.
I do not claim the slightest originality for tests given below; they are
about as old as chemistry itself, but they may perhaps be given in a
little plain form them is found in a book of chemical formulae.
Our prospector, therefore, should provide himself with the following articles.
Nitric Acid.
Muriatic Acid.
Sulphuric Acid.
Ammonia.
Potash.
Chloride of tin.
The acids and the ammonia should be in six oz. stoppered bottles and the
others in wide mouth 4 oz. bottles, also stoppered. Take also —
6 test tubes, 5 or 6 inches long, and thin.
Small pestle and mortar.
Strip of zinc.
The four bottles containing the liquids do certainly cause some anxiety if
not well packed, and I have myself ridden for days holding them in my hand
for fear they might get broken, but if they are packed in separate
divisions in a little box and spaces filled up with sawdust, is safe
enough to put them away in one's kit.
When a simple of likely-looking stuff is found, first break it up pretty
fine with the head of the pick, and then grind some of it as fine as
possible in the mortar. Put enough of the powder into one of the test
tubes to fill up about three quarters of an inch and fill up another two
inches and a half with nitric acid. Warm it with great care over a
candle, if you have one, or bit of the fire, and always heat from the top
downwards or probably the whole contents will be discharged over your
fingers. The best way to hold the test tube is to fold up a piece of
paper about a foot long and two or three inches wide into a spill and
double it in the middle of its length; this is twisted round the top of
the test tube and held by the ends.
When the powder and acid have simmered for two or three minutes let them
cool and settle. When clear, very carefully poor half an inch of the
clear fluid into another test tube and add one or two drops of muriatic
acid. It will perhaps turn cloudy and settle to the bottom after a little
while. If this has happened pour off the clear fluid, leaving the white
deposit, and pour in an inch of ammonia, shaking it up well with the thumb
on the top of the tube.
If the deposit has disappeared you have found silver.
If the deposit has turned black, Mercury.
If the deposit has not changed, Lead.
If however there was no result when the muriatic acid was added take
another half inch of the original fluid in a fresh tube and add an inch or
more of ammonia.
If it turns Blue it shows Copper.
If it turns Cloudy-white it shows Mercury.
If it turns Red it shows Iron.
Perhaps you have still no results. Then take another half inch from the
original fluid again add a drop or two of muriatic acid and dip it into
the strip of zinc.
If it turns deep black it shows Antimony.
Try again if nothing has yet turned up. Take a fresh half inch from the
original liquor, and drop in one drop of sulphuric acid.
Cloudy-white means Lead.
If still unsuccessful take a final half inch, but before doing so dissolve
in a separate test tube some potash in a little water. Then pour this
potash gradually into the other liquids.
If it turns blue there is Cobalt.
If it turns green there is Nickel.
If it turns cloudy white there is Zinc.
I should perhaps have given the test for gold first as it most likely
would be tried before all these. The best one is as follows:
Put about half an inch of the powder mineral into a test tube and stand it
aside for a few minutes while in another tube you pour
Two inches of nitric acid,
Half an inch of muriatic acid.
Pour this on the powder and heat as in the other experiment. When cool
and settled pour off the clear fluid, and having previously dissolved a
very little of the chloride of tin in water in a separate tube, drop a
little of it into the other one. If there is any gold the colourless or
yellow fluids will turn a deep purple color [sic].
If chloride of tin is not to be purchased, sulphate of iron will do as
shown in the recent lecture, but the test is not nearly to [sic]
satisfactory.
These are all the tests necessary for proving the existence of nine
principal metals. Of course the quantity analysis is a different affair,
but after some experience and particularly if the same quantities of
chemicals are used every time the prospector can gain a fair idea of
payable or non payable discoveries.
While using the expression of length, such as inch, etc., to indicate the
quantity of liquid in the test tubes, it is only to be considered
approximately except in one case which is that of the mixture of nitric
and muriatic acids in the test for gold. These must be exact, and I have
always found a good way is to lay a foot rule against the tube and measure
the contents by it.
While the blow pipe is, in the hands of an expert, more convenient and
superior to the above mentioned methods, these tests are certainly more
suited to the ordinary prospector, who only needs ordinary care and
observation to enable him to decide as to the presence of one or more
metals, and he can thus have a sure guide as to the prospects of the
ground he is investigating, avoiding, on the one hand, the annoyance of
carrying samples to town only to have them declared valueless, and, on the
other hand, saving himself from the frequent and fatal error of passing by
valuable ground as worthless because it contains something that he does
not understand nor has the means of analysing.
The cost of chemicals and apparatus that are mentioned she would hardly
exceed £1, and would last for a prospecting trip of a month or so for one
man.
Hoping that this may prove of some service to those intending to go up
country, I am,
Yours, &c.,
JOHN W. ROCK.
Perth, August 6, 1888.
