, 1902-02-11

FOUND IN THE COvELLITE COP.
PER ORES OF THE RAM
BIER MINE.
Tests Made by Professors II. L. Wells
and s. l.. Penfield Of the Sheffield
Scientific School Established Be-
yond Doubt Presence Of Platinum
in the Ores Of That Mine.

The following article on a new oc-
currence of sperrylite in the Rambler
mine is from the joint pen of H l..
Wells and S. l.. Penfield of the Shelf
field Scientific school. New Haven.
Conn. printed in the February num-
Der of the American Journal of Sci
ence. New Haven, Conn. pages IS
and SO:
Through the kindness of Prof. Will
bur C Knight of the University of Wyo-
ming at Laramie. we have received a
specimen of platiniferous copper ore
from the Rambler mine, which is sit
uated in the Medicine Bow mountains
about so miles southwest of Laramie.
The specimen consisted chiefly of COW
elite fndigo-copper) with a little py-
rite. It occurred to us that the plati-
nun in this ore might exist in the form
of %sperrylite, a platinum %arsenide,
since this mineral, which we described
a number of years ago, a. found with
sulphide ores in the Sudbury region
in Canada. and since it has been shown
by Walker that the Canadian sperry-
lite occurs chiefly in copper minerals;
hence we made an examination of the
specimen.
About an ounce of the ore was
coarsely crushed, ~decompOsed with
hot, concentrated nitric acid. and the
residue was treated alternately with
boiling. strong caustic soda solution
and nitric acid until only a very small
amount of dark-colOred residue re-
manned. When this was freed from
a little ~light-colored material by ocean
tatiOn. about six very small glittering
crystals. resembling sperrylite. were
observed with the naked eye. After
the material had been dried. the crys-
tails were readily picked out on a glass
surface by the use of a lens and needle.
Under the microscope the crystals
| showed the wonderful brilliancy Of
s%perrylite. The largest crystal meas
ured 0.12 millimeters in diameter and
was rather highly modified. Although
the combination could lot be de-
termined with certainty, the forms OF
the cube and ~pyritohedron were evil
IDENTIFY present. A second crystal was
evidently a combination of octahedron
and cube. Four crystals having a to-
tai weight OF about 100000 grams. as
Stunning that each had a diameter OF
OIL millimeters which is a generous
average. were used for a chemical ex-
animation. Upon being heated in the
open tube they refused as sperrylite
does and gave a sublimate of %arsenious
oxide in white, octahedral crystals.
The residue in the tube was dissolved
in aqua regia, and the solution, upon
evaporation with a little ammonium
chloride. gave yellow octahedral crys-
tails of ammonium platinic chloride.
There is no doubt, therefore. that the
mineral was sperrylite.
We are not sure that the ore does
not contain platinum In some other
form than sperrylite. but the fact
that we did not observe any metallic
grains with this mineral makes it prob
able that all the platinum in the ore
exists as %arsenide.
|. The discovery that platinum exists
in the ores Of the Rambler mine is
quite recent and of great interest.
Prof. knight states that platinum is
found in ores from all parts OF the
mine in quantities varying from .o6 to
IA ounces per ton (.0002 to .0O4s per
cent?, and that it is apparently most
abundant in the covellite ore. From
his account it seem probable that the
platinum in this mine will be of o n
siderable commercial Importance h
occurrences Of sperrylite in Ontario
in Wyoming and as Hidden has found
In several places in a North Carolina
district. show that the mineral is wlde
Nv distributed on this continent. 1t is
to be hoped that copper ores will mere
after be carefully examined for piati-
mum, and that future discoveries may
he made which will tend to alleviate
The nresent threatened dearth OF this
useful metal.