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Identity HelpMicro ID HELP - red crystal

16th Sep 2014 12:34 BSTRoger Curry

Size - approx 0.2mm
Shape - thin tabular hexagonal
Colour - bright red
Lustre - metallic
Transparency - opaque
Magnetism - non-magnetic
Location - Coldberry Gutter, Teesdale, UK
Outcrop rock - ironstone nodule from namurian shales
Associated minerals - quartz, kaolinite, millerite

Any ideas or suggestions for ID would be gratefully recieved. My guess and Steve Garza's can be found on this Mindat thread



16th Sep 2014 14:46 BSTHolger Hartmaier

How about vanadinite? It can occur in short hexagonal prisms.

16th Sep 2014 15:57 BSTRoger Curry

Hi Holger,

I think vanadinite would be transparent at the extreme thinness of the crystal, also the lustre is wrong - this tiny crystal reflects light like glitter.



16th Sep 2014 17:01 BSTHenry Barwood Expert

Hematite pseudomorph after pyrrhotite/smythite?

16th Sep 2014 18:23 BSTSpencer Ivan Mather

I was also thinking Hematite...

16th Sep 2014 23:57 BSTRoger Curry

So how do I determine whether this is an oxide or a sulphide? It's too small for wet analysis.


17th Sep 2014 02:05 BSTHolger Hartmaier

Would immersing the crystal in various kinds of fluids of known density, such as used in gemology work? At least you could obtain a specific gravity. Also, I wanted to ask if the "glittery" reflections you described were due to surfaces on the crystal itself or due to some secondary mineral coating.

17th Sep 2014 10:28 BSTRoger Curry

Good suggestion Holger, unfortunately I haven't the facilities for either density measurement or any further microscopy - better photos would help. I think perhaps I will try to get someone interested in my nearest university. Would a scanning electron microscope be the best route? Perhaps the X-ray analysis from the 'scope be able to nail down what this is.

Does anyone have a suggestion about who to approach at Durham University? Perhaps someone in the Dept of Earth Sciences will be into local minerals enough get some images and qualitative analysis. I can't go the commercial route.



18th Sep 2014 20:15 BSTRoger Curry

Hi all, mystery "crystal" ID!

See the companion thread


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