The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1917-10-04


cal survey, gives the following useful
suggestions for prospecting. Platin-
| UNI is not known in all countries, but
that all the deposits are known Is
highly improbable. In fact platinif-
erous deposits in southern Spain have
been discovered recently by geolo-
| gist working on the assumption that
the place to look for platinum is IN
areas of basic igneous rocks. similar
to the typical Russian rocks. System
attic search, based on similar assump-
| ton, in all countries may lead to the
discovery of new deposits of platinif-
erous gravels of economic importance,
sounded In Russia such systematic
work has been in progress for many
| years and although new deposits have
been found they are not so numerous
iplorers anticipated.
| Platinum, both as the native metal
and in the form of sperrylite, (platin-
UNI arsenide) has been found in ba-
sic igneous rocks in several places in
the world but not in commercial guam
titles The search for the source of
platinum in rocks is therefore not
| likely to be of particular value in
obtaining an immediate supply of the
metal from lode deposits; it may,
however, develop nearby gravel depos-
| it's AS already stated, 1t is confid-
emily believed that any platiniferous
ores of commercial grade will yield
to the regular analytical treatment in
the hands of competent assayers.
The placer deposits containing plat
mum are all, so far as known, in the
vicinity of areas of basic igneous
rocks, and it would seem that in any
search for new deposits of platinif-
erous gravels the first. step is the
search for outcrops of peridotite, pyr-
oxenite, dunite and serpentine. When
areas of these rocks have been found,
the grayels of the streams rising in
them should be washed to ascertain
if platinum is present. The heavy
concentrates found in gravels carry
ing platinum are usually rich in chro-
mite and Divine. The character Of
the rock particles often gives clue
to the source from which the gravels
were derived.
Crude platinum, as it occurs in pla-
Ger concentrates, is ordinarily a sill
very white metal which could be con-
fused only with silver and possibly
pieces of iron or steel 1t can be dis
tinguished from both of these metals,
as they are soluble in dilute nitric
acids; crude platinum can be dissolv-
ed only in concentrated aqua regia. In
some placer deposits the grains of
platinum are coated with dark film
and somewhat resemble the grains of
the dark minerals chromite, magne-
tite or ilmenite, from which they are
separated by careful panning, as the
specific gravity of platinum is great
er than that of any of those metals.
Platinum will not amalgamate with
quicksilver alone, but will amalga-
mate if sodium is added In ordinary
quicksilver amalgamation the flakes
of platinum float ON the surface and
can be recovered If sodium amalgam
is used the platinum may be separat-
ed from gold by agitating the ANAL |
gam with water until all the sodium
is used up to form sodium hydroxide;
then the platinum will come out on |
the surface of the amalgam, provided, |
of course, the amalgam is sufficiently /
liquid. Platinum has hardness of
to s. and can be scratched with a
knife, 1t is so malleable that it can
be pounded without heating into very
thin sheets. 1t is practically infusible,
the grains can not be melted together,
as can particles of gold
A relatively simple chemical test
can be made to determine the platin-
UNI. The metallic particles are dis
solved by boiling in concentrated aqua
regia and the resulting solution is al
lowed to remain on the stove till dry.
The residue is dissolved again in n.y.
irochloric acid and evaporated by
polling till the solution is thick but
lot quite dry This mass is dissoly-
I'd in distilled water and few drops
If sulphuric acid and Of potassium
odde solution are added, which, in
he presence of platinum, causes the ,
olution to turn characteristic wine .
ed, if much of the metal is present, or
0 reddish pink in the presence of
mall quantities of platinum.
The test outlined above is fairly Il
elicate, but it can not be used to de-
ect traces of platinum in the presence
{ large quantities of iron or other
dement's.
A second test may be applied to the
qua regia solution after the resolu-
on in hydrochloric acid outlined