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PhotosMillerite - Thompson Mine, Moab-Setting Lakes area, Thompson Nickel Belt, Manitoba, Canada

3rd Jul 2013 17:45 UTCRichard Gunter Expert

Millerite

Thompson Mine, Moab-Setting Lakes area, Thompson Nickel Belt, Manitoba, Canada

The T2 portion of the Thompson Formation and the T2 Pit have nothing to do with each other, just a convergence of names. The open pit sequence in the Thompson area was based on surface geographic location. In the calcareous metasediments of the Thompson Formation the Millerite veinlets form within a roughly orthogonal network of fractures, much as your sample does. The more common Millerite occurrence from Thompson is in fractures within the massive sulphide.

4th Jul 2013 19:53 UTCRob Woodside 🌟 Manager

Thanks Richard. What hierarchy would you suggest for the Thompson Mines?

4th Jul 2013 21:09 UTCRichard Gunter Expert

Hi Rob:

As far as I am aware all of the Thomson Mines, both underground and open pits, exploit a single ore body with essentially the same mineralogy. I do not know the exact location of the Thompson Mine Cubanite crystals but I assume they are from one of the underground mines in fractures in the sulphides. The massive sulphide ore will host all of the sulphide mineralogy except for a few of the late-stage veins that carried Millerite and Calcite-Pyrite into the overlying metasediments of the Thompson Formation. Therefore the Thompson Mines should be treated as one location with sub-locations, such as the 1A Pit for my Millerite, when the samples are personally collected.

Birchtree and Pipe II (the Pipe Pit is the main mine here, the underground Pipe Mine was not large) have very different geological settings and a different mineralogy than the Thompson Mine.

Richard Gunter

6th Jul 2013 00:13 UTCVik Vanrusselt Expert

Hello all,

I stumbled upon this thread about one of my specimens by chance but I'm glad I found it anyway :-)

Since English is not my first language, I'm having difficulty understanding whether or not there is an actual "T2 Pit" at the "Thompson Mine",

or just a "T2 portion of the Thompson Formation" (i.e. "NO, there is NO actual T2 Pit" and the wording on the label that came with the specimen is to be considered "wrong").

I've found another reference to a certain "T2 Zone" here: http://www.geologyontario.mndmf.gov.on.ca/gosportal/gos?command=mndmsearchdetails:mdi&uuid=MDI000000001218

Could someone please clear this up for me?

Thanks,

Vik

8th Jul 2013 18:22 UTCRichard Gunter Expert

Hi Vic:

Your reference has nothing to do with Thompson. It is an Province of Ontario website concerning deposits in their province. The Thompson, Birchtree and Pipe deposits are in the Province of Manitoba.

There probably is a T2 pit but it has nothing to do with the T2 portion of the Thompson Formation. Inco accessed the near-surface portions of the Thompson deposit with a number of small open pits. T1 and T1A were the only pits open when I visited but there were plans for more. The T2 pit was the next one to be opened as INCO numbered them geographically from the surface. They are all small pits and the bulk of the ore in Thomson is produced from underground workings. There is a T2 shaft at Thomson as well so it is easy to become confused. Millerite samples were found both in the open pits and underground. It appears from the matrix that your sample comes from the calcareous metasediments overlying the massive sulphides. Check my posted Millerite sample as it comes from the metasediments as well and the picture is too large to post here. Most of the Millerite from Thompson on the market comes from fractures in the massive sulphides.

Hope this helps.

Richard Gunter

8th Jul 2013 23:28 UTCVik Vanrusselt Expert

Thank you Richard for this explanation.

I will remove the link to the document from the caption to not complicate things further.

Vik

8th Jul 2013 23:32 UTCRichard Gunter Expert

Hi Vic:

Sounds good. Happy to be of help.

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