Little Gem prospect, Lillooet Mining Division, British Columbia, Canadai

Regional Level Types
Little Gem prospect	Prospect
Lillooet Mining Division	Division
British Columbia	Province
Canada	Country

The following quote is from B.C. Government site “Minfile”- Minfile No. 092JNE 068:
“The Little Gem prospect, a hypothermal cobalt-sulpharsenide uranium and gold vein, 2.3 kilometres east northeast of Dickson Peak, lies within the margin of the Jurassic to Tertiary Coast Plutonic Complex (Cretaceous Penrose lobe pluton). Host rocks consist of granodiorite, minor hornblende-biotite-quartz diorite, diorite and gabbro, which are intruded by feldspar porphyry dykes. A broad, east trending and steeply south dipping fault zone cuts the granodiorite near the eastern contact with older sedimentary and volcanic rocks of the Mississippian to Jurassic Bridge River Complex (Group).
Shears in the zone contain two parallel ore shoots ranging in width from a few centimetres to a few metres. Irregular lenses of almost solid sulphides contain cobalt and gold values in association with danaite, loellingite, safflorite, arsenopyrite, scheelite and minor molybdenum. Uranium, in the form of uraninite, occurs in the gangue along with coarse-grained allanite, apatite, feldspar, quartz, chlorite, sericite, calcite, erythrite and limonite. Gold occurs mainly as microscopic veinlets of the native metal within and adjacent to the sulpharsenide minerals. Surrounding the ore, strongly bleached and sericitized granodiorite containing disseminated sulphides, residual quartz, feldspar and kaolin grades into unaltered granodiorite. The metallic minerals occur with the gangue in coarsely crystalline masses but are in general younger than most of the gangue minerals. The combination of the batholithic host rocks and the association of uraninite with hornblende, biotite, apatite, allanite, monazite, orthoclase, cobalt sulpharsenides, arsenopyrite and molybdenite is indicative of high temperature, possibly magma-derived, hydrothermal fluids.”
Further comments by Giles Peatfield regarding minerals reported:
The following minerals have been X-ray confirmed: allanite, calcite, clinochlore, glaucodot/alloclasite, muscovite and safflorite.
I have retained “danaite” even though it is no longer considered a valid species. This is because it was X-ray confirmed in the early days, and has been reported up to the present day. It is a cobalt-rich arsenopyrite – Carson (1984) quotes Co analyses of 8-9% Co.
Carson (1984) also describes the skutterudite as having “about 20% Co.”
Although I have not listed them, McColl (1949) mentions zoisite and “possible” autunite.
The whole subject of the cobalt-bearing sulfarsenides, etc. is complex and not fully resolved. More detailed work would be necessary.
The rare earth element bearing minerals allanite, bastnaesite and monazite were identified by X-ray and electron microprobe studies (Clemson, 1985).
The gold-bismuth mineral maldonite (Au2Bi) was reported (Carson, 1984), who implied that the identification was by electron microprobe analysis, but there are no supporting reports available to me. As this is an uncommon mineral, for which this is only the fourth Canadian occurrence that I have been able to find, caution is advised. If anyone has more data, please post a discussion.
There has been a large amount of test work directed at trying to design a process to recover the cobalt, gold and uranium values in the mineralized material. Such work is beyond the scope of this report.

Giles Peatfield
BASc. (Geological Engineering) University of British Columbia 1966.
PhD Queen's University at Kingston 1978.
Worked for Texas Gulf Sulphur / Texasgulf Inc. / Kidd Creek Mines - 1966 to 1985.
Consultant 1985 to 2016

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Link to British Columbia Minfile:	092JNE068

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