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PhotosMolybdenite - Zircon showing, Saranac properties, Monmouth Township, Haliburton Co., Ontario, Canada

29th Dec 2014 15:31 UTCRichard Gunter Expert

Should these Molybdenite samples be in the Skarn Showing rather than the Zircon Showing? My Molybdenite sample was found along the trail to the Zircon Showing and not in the Zircon pegmatite itself. It came from a loose skarn boulder next to the trail, about 200 feet northeast of the Zircon pegmatite.The skarn where the sample was found was heavily overgrown with little rock exposure and no trench was present.

29th Dec 2014 16:13 UTCReiner Mielke Expert

I would say the Skarn if you are sure it isn't a boulder from the pegmatite. What is the matrix on the piece? Is it consistent with a skarn?

29th Dec 2014 16:16 UTCRichard Gunter Expert

Hi Reiner:

I will transfer it.

29th Dec 2014 17:15 UTCRichard Gunter Expert

The matrix is a rusty carbonate and not the Quartz and feldspar of the Zircon pegmatite. The Molybdenite in this showing occurs as distinct hexagonal crystals and does not have the aggregated appearance of the Graphite spheres for some reason.

29th Dec 2014 18:10 UTCJohn A. Jaszczak Expert

Hi Richard,

I would double check the identification. I have a lot of graphite from the Saranac area, including some

that look like your specimen. It is easy to mistake graphite for molybdenite. The specimen shown hints

at graphite to me. One way to tell is to use a streak, but it is best to compare the streak side by side

with known graphite and known molybdenite. Then you can really tell the blue hue in

the molybdenite streak.

Sincerely

John

29th Dec 2014 18:19 UTCRichard Gunter Expert

Hi John:

I have done that with a Molybdenite sample from the Long Lake Mine, Ontario and a massive Graphite from Madagascar. The streak on this sample matched the Molybdenite sample and was quite different than the Graphite. I originally collected this as a Graphite sample but it looked too much like the Long Lake Molybdenite so I checked it.

29th Dec 2014 18:21 UTCJohn A. Jaszczak Expert

OK thanks for the additional information Richard.

If you would want to be doubly sure, you could send me a small cleavage of the moly (even ~1 mm is

enough) and I could check with Raman.

Cheers

John

29th Dec 2014 18:26 UTCRichard Gunter Expert

Hi John:

Do you know if Molybdenite and Graphite can occur in equilibrium at the skarn locality? I have not heard of the two phases occurring together. I did not see any of the Graphite spheres when I collected this sample. Does the Graphite occur as hexagonal crystals as well as spheres at this locality?

29th Dec 2014 18:43 UTCJohn A. Jaszczak Expert

The graphite at different spots there occurs as both spheres (in the calcite) and flakes/hex crystals.

I don't have any molybdenite from Saranac, and rather doubt they occur together. I know of only very few

localities with graphite and molybdenite together (literally in contact), or in the same specimens.

John

29th Dec 2014 19:15 UTCRichard Gunter Expert

Hi John:

The rusty coloured carbonate was pervasive throughout the boulder and I did not see any white carbonate. It is possible that the Molybdenite occurs in an Fe-rich layer. This would be consistent with the Long Lake Mine where the Molybdenite crystals occur disseminated with Pyrite in layers within a white dolomite marble. There would have to be a lot of outcrop cleaning at the Saranac site to be certain.

29th Dec 2014 20:02 UTCJohn A. Jaszczak Expert

I could check your Long Lake sample as well if you like. I have personally never seen molybdenite

in dolomite or calcite that I can think of off hand.

Sincerely

John

29th Dec 2014 20:17 UTCKelly Nash 🌟 Expert

My graphite photo (Saranac graphite photo-180236) should be moved to the skarn showing also (I can do that myself later). I didn't find it at the zircon location, but along the road where the skarn is exposed. I would bet the other one is from there also. I like the way the three sublocalities are arranged now and "Saranac Properties" is a good name (with Saranac Mine in parenthesis).

29th Dec 2014 20:20 UTCReiner Mielke Expert

Hello John,

This is an example of moly in calcite, the same unit contains abundant graphite. I didn't believe it was moly so I had him send me a sample to test and it was moly. http://www.mindat.org/photo-243825.html

29th Dec 2014 21:12 UTCRichard Gunter Expert

Hi John:

The Long Lake Molybdenite was characterized as a minor phase in the Sphalerite ore and is mentioned by Sabina. I do not think Graphite was ever found at Long Lake. My posted sample came from the ore pile during zinc production at the active mine in 1973. The mining was underground so the Pyrite-Molybdenite in the ore pile did not have a chance to oxidize.

29th Dec 2014 21:32 UTCJohn A. Jaszczak Expert

Thanks Richard, I just looked up your Long Lake molybdenite photo. That looks pretty consistent to me.

(But the Saranac piece is so similar to my graphite from there.)

Thanks Reiner for your post. That's pretty interesting. I agree the photo makes it really look like graphite. How did

you test it?

Best wishes,

John

29th Dec 2014 21:58 UTCRichard Gunter Expert

Hi John:

I will test another sample of the Molybdenite from Saranac against the Molybdenite from Long Lake but the first streak test I did looked very similar to Molybdenite and not like the black of Graphite. Where was your Saranac Graphite found?

29th Dec 2014 22:31 UTCReiner Mielke Expert

Hello John,

Streak test. As you know moly has a very distinctive streak quite different from graphite.

30th Dec 2014 17:11 UTCRichard Gunter Expert

Hi John:

I tried the streak test on another grain from this sample on unglazed porcelain. The grain did not smear but disintegrated into finer particles that left a greenish-black powder on the white porcelain. This is not the response I would expect from Graphite. The crystals are very flexible and slightly sectile; they bent and deformed when I tried to remove the sample grain from the matrix. Is this the response you get from your streak tests?

30th Dec 2014 17:36 UTCJohn A. Jaszczak Expert

Hi Richard,

Disintegration seems a bit odd, but the greenish-black color is right for graphite. Molybdenite

has a blue hue.

John

30th Dec 2014 17:48 UTCRichard Gunter Expert

Hi John:

I thought Graphite gave a deep black colour and smeared on a streak plate. Does the very well crystalline Graphite behave slightly differently from the massive Graphite? The disintegration was very similar to the behavior of the Molybdenite grain and not at all like the massive Graphite which smeared to a powder.

30th Dec 2014 18:10 UTCJohn A. Jaszczak Expert

Yes, in fact highly crystalline graphite's streak is more metallic than massive graphite, the latter which tends to have a blacker streak. If you streak a piece of paper (heavily) and send it to me, that may be all I need tor an analysis.

John

30th Dec 2014 18:15 UTCRichard Gunter Expert

Hi John:

I will pull off a few grains and send them to you. Please send me your address by PM.

13th Jan 2015 21:20 UTCJohn A. Jaszczak Expert

For those interested, the grains I received turned out to be graphite, verified by Raman spectroscopy.

Cheers

John

13th Jan 2015 23:06 UTCRichard Gunter Expert

Hi John:

I have changed the entry for the sample.

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