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prcantos
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Joined: 17 Apr 2012
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Location: Granada (Spain)
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 Posted: Jan 20, 2014 17:52 Post subject: Black adularia in limestone |
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Hi. I have got this specimen labeled "black adularia with pumpellyte in limestone" from Potrero Chico, Monterrey, Mexico. I wonder how these idiomorphic feldspar crystals have grown in a limestone, but I am not able to find any information about this assemblage of minerals (feldspar and pumpellyte in limestone) or this locality.
Could you please help me about this specimen, the rock in the matrix, or the formation -or alteration- of this assemblage of minerals? Thank you very much.
| Description: |
Black adularia and pumpellyte in limestone
Potrero Chico, Mun. de Sabinas Hidalgo, Nuevo León, Mexico
4 x 3'5 cm.
General view. |
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12315 Time(s) |
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| Description: |
Black adularia and pumpellyte in limestone
Potrero Chico, Mun. de Sabinas Hidalgo, Nuevo León, Mexico
50X
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12289 Time(s) |
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Pablo Rodríguez Cantos
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newryqs
Joined: 30 Aug 2013
Posts: 44
Location: NY
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| Posted: Jan 21, 2014 17:03 Post subject: Re: Black adularia in limestone |
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The species are reported from the locality at Mindat. What is left is to verify that your minerals are correctly identified. Have you checked the hardness of the adularia? If you break one of the grains of the mineral, does it show cleavage?
best Wishes, Van
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alfredo
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| Posted: Jan 21, 2014 17:30 Post subject: Re: Black adularia in limestone |
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| I suspect that this might be teruelite and not adularia?
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Pete Modreski
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Joined: 30 Jul 2007
Posts: 709
Location: Denver, Colorado
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| Posted: Jan 21, 2014 18:01 Post subject: Re: Black adularia in limestone |
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| I was going to write about what an interesting rock/question this is, and perhaps questioning whether the black crystals are really adularia, but I think that Alfredo has hit the nail right on the head (as we say here); those black crystals look exactly like the photos of "teruelite" that are posted on mindat! I'm sure that's what they are. Bravo, Alfredo!
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prcantos
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Joined: 17 Apr 2012
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Location: Granada (Spain)
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| Posted: Jan 23, 2014 09:51 Post subject: Re: Black adularia in limestone |
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Ok, I think that you are right, but the label is wrong! Teruelite is a good identification. I have checked the hardness: the black crystals scratch the fluorite lightly, but not the apatite; so it can't be adularia (K-feldspar). And teruelite fits well with the matrix.
Thank you very much!
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Pablo Rodríguez Cantos
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newryqs
Joined: 30 Aug 2013
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Location: NY
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| Posted: Jan 23, 2014 10:10 Post subject: Re: Black adularia in limestone |
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| Does it fizz slowly in HCl?
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prcantos
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Location: Granada (Spain)
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| Posted: Jan 23, 2014 12:17 Post subject: Re: Black adularia in limestone |
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The matrix does it quickly, it is indeed a limestone; but I haven't checked it with the crystals, I will do it.
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Pablo Rodríguez Cantos
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prcantos
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| Posted: Jan 30, 2014 10:32 Post subject: Re: Black adularia in limestone |
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| newryqs wrote: | | Does it fizz slowly in HCl? |
Yes, it hardly fizzs in cold HCl, but it does it intensely when you heat it up!
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Pablo Rodríguez Cantos
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newryqs
Joined: 30 Aug 2013
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Location: NY
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| Posted: Jan 30, 2014 10:56 Post subject: Re: Black adularia in limestone |
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Did you find any pumpellyite?
best Wishes, Van
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prcantos
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Location: Granada (Spain)
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| Posted: Jan 30, 2014 13:01 Post subject: Re: Black adularia in limestone |
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No, I think there isn't any (look at the micro, I can't see it). I suspect that the label "adularia + pumpellyte" is wrong. Maybe the locality is also confused! Thank you.
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Pablo Rodríguez Cantos
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Rodney B Jackson
Joined: 13 Dec 2013
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| Posted: Feb 05, 2014 17:44 Post subject: Re: Black adularia in limestone |
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| I'd go with teruelite flecks.
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newryqs
Joined: 30 Aug 2013
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Location: NY
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| Posted: Feb 05, 2014 18:58 Post subject: Re: Black adularia in limestone |
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Localities may be correct. The species are more commonly wrong.
Best Wishes, Van
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