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LocalitiesNorth quarry, Dundas Quarry, West Flamborough Township, Hamilton, Ontario, Canada

26th Sep 2011 14:16 UTCAndrew Haighton

I have been puzzling over a mineral which was found in the Dundas Quarry (North Section) for a while. I picked up a large rock ~80 pounds, and smashed it into smaller bits roughly 5 years ago. The rock was heavily oxidized brown and contained numerous Galena cubes, Calcite crystals, and what appears to be spherical Sphalerite crystal growths around a yellow mineral (possibly sulphur). Sphalerite is also noted on the specimen.


Then there is this mineral, which is much smaller than 1 mm, so scratching it would be impossible. It does not fluoresce under short or long wave UV, and forms tapering crystals with hexagonal cross-section. It is red to brown, and also yellow to orange. as shown in the attached photos.


I was leaning towards Wurtzite as...


1) Sphalerite and Wurtzite are of the same formula, and Sphalerite is quite common in this quarry.

2) The colour and shape are very similar to that of specimens of Wurtzite in the MINDAT gallery,

3) Some of the crystals are on the outside of the spheres have these crystals attached to the Sphalerite balls, which would be fitting with a collophorm texture (checking my textbooks from back in my geolab days), which are Sphalerite with Wurtzite and Sulphur.


In the viscinity of the mystery crystals are Galena cubes as well as Dolomite crystals.

Any thoughts would be greatly appreciated.

26th Sep 2011 15:30 UTCAlain Hanson Expert

Hi Andrew

I am not familiar with the occurrence, but beside wurtzite wich is a good guess, your description (red or yellow hexagons stacked in inverse pyramids) and the paragenesis could also fit greenockite

Greetings from Belgium

Alain

26th Sep 2011 16:45 UTCAndrew Haighton

Hi Alain;


I have to admit, Greenockite was another thought I had, though, how would you determine if it was one or the other. The association with the Galena, and the fact that it in oxidized rock (dolomitic limestone hostrock, with occasional shaley zones predominantly in this quarry) lead me to believe that the crystals may be more than just Sphalerite. Oh, and the crystal form doesn't conform to anything else I have seen there.


Andy

27th Sep 2011 18:01 UTCUwe Kolitsch Manager

I agree with Alain that it's most probably wurtzite.

27th Sep 2011 18:18 UTCAndrew Haighton

Hi Uwe;


I had been puzzling over this one for a while. There was no record of Wurtzite at this quarry, but all the signs pointed that way. It's always good when your gut feeling seems to be right. That being said, I have been in contact to a collector in the states who would get it analyzed. Never hurts to be 100% sure.(tu)


Thanks.


Andy

2nd Nov 2011 14:15 UTCAndrew Haighton

Hi All;


The crystals have been sent in for analysis (attached). The crystals sent in were described as "Long, thin with smooth faces, but different from Sphalerite". The Fe spike is in excess of 8% I am told, though Wurtzite is up to 8%.


I am unfamiliar to this analysis, so I put it out ... What are these crystals, Wurtzite? What ever we come up with, I will set up in Mindat.


Thanks


Andy Haighton,

Brampton, Ontario.

2nd Nov 2011 18:56 UTCReiner Mielke Expert

You cannot differentiate between Wurtzite and Sphalerite based on chemistry. The difference is structural so you would need XRD.

7th Nov 2011 15:33 UTCAndrew Haighton

Hi Reiner;


Thanks for the input. Just need some clarification.


The Chemical Analysis indicates Sphalerite or Wurtzite, but the crystal shape is clearly not Sphalerite (6 sided and tapering). Would this then indicate Wurtzite without the XRD as Sphalerite does not do this?


If not, what else could it be?


Andy Haighton,

Brampton, Ontario

7th Nov 2011 21:14 UTCReiner Mielke Expert

Wurtzite is what it would be unless there is such a thing as sphalerite pseudomorph wurtzite? Anyone know of such a thing?

12th Dec 2013 14:30 UTCLiz Fodi

There are 3 images of specimens from this locality showing a yellowish-white material labeled 'Dolomite'. This was tested and verified by the Royal Ontario Museum as barite 8 years ago. It was tested and again verified at the ROM in the past year by Tony Steede as BARITE.

The purple colouring is definitely caused by the presence of fluorite.

12th Dec 2013 14:34 UTCAndrew Haighton

Thanks Liz;


I will change the description.

14th Dec 2013 17:19 UTCRob Woodside 🌟 Manager

Thanks Liz, Baryte added.
 
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