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 Post subject: Mystery Mineral
PostPosted: Tue Feb 14, 2012 11:45 am 
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Chris (aka calic) emailed me a couple photos of what appears to me a micaceous mineral asking for an ID.
What do you think?
Image

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 Post subject: Re: Mystery Mineral
PostPosted: Tue Feb 14, 2012 12:17 pm 
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Curiosity...it has metamorphic attributes, but what could those euhedral crystals associated with it be?


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 Post subject: Re: Mystery Mineral
PostPosted: Tue Feb 14, 2012 12:34 pm 
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hi,
there seem to be two different minerals in this sample: the white crystal, and the reddish matrix.
For each, try the following:
-hardness test: does the mineral scratches finger nail? does it scratche copper? does it scratch glass?
-streak color on rough white porcelain? (I mean on porcelain that is unpolished and with no enamel on it)
-also, for the white crystal, add a drop of white vinegar and watch carefully if there is any bubbling (if any doubt, listen carefully, effervescence makes 'pshhhhtt').
-when you hold it in your hand, does the whole sample feels quite heavy for it's size, or does it weight average?

also, try to get a neat close up pic of the surface of the reddish material so we get a better idea of it's structure, which you could also describe verbally btw.
Notably I wonder what is the color of the shiny particles seen in your pic: are these actually red, or are these more like whitish/grayigh/yellowish but mixed in a different reddish material.
Also a good pic of the larger crystals showing their geometrical shape (i think I cansee two of them, one whitish, and one covered with red particles?)
If the whitish crystal show cleavage cracks/planes, or cleavage surfaces, also take a picture of picture these.
Better take pics in the lght of the day (rather than in incandescent light)

Also, as there is lots of the reddish thing particles that separated from the matrix, examinate one under the scope (or with the loupe) in transmitted light to check whether it is transluscent or opaque, and also in incident light to see what structure this tiny particle shows (maybe you can see crystalline shape, or cleavage, or lamellar aggregation or whatever)

important too: detailled locality of origin?

ps: I'm not sure I will be able to help but proceeding to these few verifications would be a good starting point.


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 Post subject: Re: Mystery Mineral
PostPosted: Tue Feb 14, 2012 4:35 pm 
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Hello, my name is Chris. I emailed Barbra from a link I found when I was looking for information about this rock. I know nothing about rocks, minerals or gems. I found this one in my storage area when I moved to Vancouver years ago and have been toting it around ever since hoping to figure out what it is. Anyway, I've printed off your suggestions and will attempt to get as much of that done over the next few days. I will post more pictures and as much of the information you asked for as I can.

Thanks everyone for your interest. I'm looking forward to knowing what this is.

Chris


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 Post subject: Re: Mystery Mineral
PostPosted: Tue Feb 14, 2012 10:33 pm 
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It looks to be micaceous/specular hematite over feldspar crystals

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 Post subject: Re: Mystery Mineral
PostPosted: Sat Feb 18, 2012 3:20 pm 
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maybe calcite, dolomite or barite rather than feldspar


Last edited by cascaillou on Wed Nov 13, 2013 12:48 pm, edited 1 time in total.

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 Post subject: Re: Mystery Mineral
PostPosted: Fri Aug 09, 2013 12:21 pm 
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hematite with quartz


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