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Please ID - Chromite? Chromiumite?

Posted by claire Brimson  
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claire Brimson April 09, 2012 05:48AM
Hi

These were found again in Kemi, Finland. Kemi apparently has a Chromium plant/mine area which is outside of Kemi, these were found near the harbour.

Are the crystals Chromite? Why is the rock purple? Streak was blackish.

Also, when white light shines onto it, the purple becomes very strong purple colour. Why is that?

Many thanks

Claire
open | download - 003.JPG (165.5 KB)
open | download - 007.JPG (138.1 KB)
open | download - 009.JPG (207.5 KB)
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Ronald John Gyllenhammer April 09, 2012 01:53PM
Hi Claire,

I think you're correct about the little black octahedral crystals being Chromite. This looks very much like Chromite ore. I think that the purple colored mineralization may be Chromian Clinochlore like this: http://www.mindat.org/photo-108220.html Good luck with it.

Ron
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Alfredo Petrov April 09, 2012 02:20PM
Claire, Check whether the colour looks different under tungsten filament (incandescent) light bulb, and under fluorescent tube lights. That's sometimes interesting for purple minerals coloured by chromium.
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Eligiusz Szełęg April 10, 2012 07:00PM
looks like chromite with chromian clinochlore (form. kammererite)
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Lefteris Rantos April 11, 2012 10:09AM
Also keep in mind that much (if not most) "Chromite" is actually not Chromite stricto sensu (i.e. Fe-dominant) but rather the Mg-dominant analogue Magnesiochromite. It is safer to label "Chromite-Magnesiochromite series".

Lefteris.
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claire Brimson April 11, 2012 05:41PM
Many thanks for the information :)

I have doen a bit of 'digging' - http://en.gtk.fi/ExplorationFinland/Moreinfo/kemi.html

Hope you can get into this site - interesting :) The rock is Chromitite
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Ilkka Mikkola April 11, 2012 06:39PM
Hello Claire
Magnesiochromite has not been found at Kemi. It is chromite (Hytönen, K. Suomen Mineraalit 1999). Chromitite is an error,
it should be chromite ore.

Ilkka
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Franz Bernhard April 12, 2012 05:06AM
"Chromitite" is a petrological term / rock name.
"Chromite ore" is a technical / mining term.
Franz Bernhard
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Rock Currier April 13, 2012 04:03AM
Another reason to get our dictionary of mining, mineral and related terms running.

Rock Currier
Crystals not pistols.
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