Aberdeen herald. [volume] (Aberdeen, Chehalis County, W.T.) 1886-1917, 1900-07-26
VIEWS Of PRACTICAL MINER
Accurate Sampling Essential
to Accurate Assaying.
SOME QUESTIONS ANSWERED
PSetests Against the Use Of Assay Cor
tlAcates ~ documentary EvidenCe~
Assayer's Duties.

tincates ~ Documentary Evidence
Assayer's Duties.
Accurate sampling is quite rs essen.
tial .as accurate assaying, for 1t the
sample does not truly represent the lot,
or mass, from which it was taken. the
subsequent assays will be valueless.
The assayer OF chemist will usually re.
ceive the samples already prepared.
but ~ he will occasionally be called
upon to take his own sample a knowl'
edge OF the art Of sampling is essen.
tial."
In the Northwest q majority Of the
taken by the prospector, or other'inter'
ested party. and as the assay certifi'
Gates are often used ~ the document
a,y evidence Of the value of the profas.
IT,, the assayer should be very careful
to state on the tace OF such certificates
exactly from whence he obtained the
sample on which the assay was made.
Ii an assayer samples the ore him.
self, he owes it to his client 20 to state.
as it doubles the value OF the certifi'
cate. If he did not take the sample
himself he should place the response.
bility of the sample where it belongs.
by stating who did take it. Without
some one known vouching for the ore
Of the sample, assay certificates should
carry no weight NJ documents. This
can hest be accomplished by the as
sayer seeing to it that his printed Ger.
tificate blank is worded to cover the de.
sired points, telling the whole story
and protecting him from any after talk.
must protest. also. against sthe
habit OF certain assayers in filling in
the value OF the ore on the assay certid.
cate, as they do, ut the price of the
metal in marketable shape delivered in
New York. 1t shows a gross ignOr-
ance on the part OF the assayer rs to
the value OF the ore here. and often
misleads the prospector frightiully. at
the same tine iurthering and opening
the door for fraudulent practice. l
have seen, this summer. assay certifi.
Gates upon which the copper Of 5 per
cent IRE was figured out at Is cents.
equal to $18 per ton, whereas no smelt'
or could afford to pay more than about
one.third that price.
a good practical rule to use in figur'
ing out approximate values OF q sui
phide ore, at present market quota
lions, il as follows:
copper the ore contains.
Allow 40 cents for every per cent OF
lead the ore contains.
Allow 80 cents for every ounce of
silver the ore contains.
Allow $40 for every ounce of gold
the ore contains.
These values are for ore delivered on
the line OF railway.
The prospector has to sample his
own claim and wishes to know the
truth. Naturally. ask how he is to
do it, and the following remarks are
for his benefit. not for the professional:
In sampling 4 lead, ii the vein is SO
that it will all have to go tor treat.
ment, a section OF uniform thickness
right across the whole face of the lead
should he taken for ore samples.
Another, and quite as satisfactory
method, is to sample all the rock that
comes out OF the prospect, or sample
the dump, ii there is any. by cutting
channels through it on the same princi'
Pile as in sampling ledge.
1t must always be borne in mind in
sampling that there is liable to be a
great difference between the dump and
the fine ore, and consequently a due re.
gard must he had to getting the proper
proportion OF each.
Hand-picked samples are never reli.
able, aud should always be avoided.
Experienced mining men frequently
take hand samples OF particular classes
OF the ore in u mine. have these assayed
and often from these results they esti.
mate what grade of ore they are min.
ing. This may be correctly done, and
it il wonderful how close to correct
assays experienced men can guess"
but it is uncertain at the best, and
dangerous for inexperienced persons to
attempt to be guided by such estim'
mates.
Assays cannot be averaged, unless
one KNOWS tuo Actudi W0IKut VI tIic Iud'
terial represented by each assay. and
only then by long calculation, too
long to describe here. except briefly.
In nine cases out OF ten when the
"average assay OF mine" is spoken OF.
it is incorrect and is usually obtained
by adding up number OF separate as
says and dividing the sum by the mum.
hers Of such assays. 1t quite correct
to take an average sample, have that
assayed. and call 1t the average assay;
but this is seldom done. The correct
average assay may be obtained by mul.
tiplying the weight OF each lot OF the
ore by tire assay OF such lot. and the
product of such multiplication and
divide this sum by the sum of the
weights OF the various lots of the ore.
The quotient OF such division will be
1.-THE only correct average assay" obtain.
able. u. NJ. ROSENDALE,
In Portland Telegram.
Cmstl~ Crag Tavern burned.
Dunsmuii. Cal, July 2S.-Castle
Crag Tavern, fashionable summer
resort in the Sierra mountains, was
DESTROYED bv fire, together with its