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Old St. Andreasberg specimen of Arsenic, Pyrargyrite and ?
  
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GneissWare




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PostPosted: Apr 16, 2017 10:20    Post subject: Old St. Andreasberg specimen of Arsenic, Pyrargyrite and ?  

I am trying to identify some of the small crystals on this circa 1900 specimen from Germany, particularly the fine (small) silvery gray material covering much of the specimen, and the reddish inclusions in the lustrous, quite clear Quartz points. Hopefully, one of the German collectors has seen this before, as Mindat is not of help. Thanks!


IMG_8456.JPG
 Mineral: Pyrargyrite with Quartz
 Locality:
St. Andreasberg, St. Andreasberg mining area, Goslar District, Harz, Lower Saxony/Niedersachsen, Germany
 Dimensions: 91 x 90 x 24 mm
 Description:
Dark, blocky crystal seems to be a 5-6 mm Pyrargyrite. The silvery grey material coating much of the specimen may be Arsenic, and the reddish points look like Quartz with inclusions of an unknown.
 Viewed:  1414 Time(s)

IMG_8456.JPG



IMG_8455.JPG
 Mineral: Pyrargyrite with Quartz on Arsenic
 Locality:
St. Andreasberg, St. Andreasberg mining area, Goslar District, Harz, Lower Saxony/Niedersachsen, Germany
 Dimensions: 91 x 90 x 24 mm
 Description:
The underlying dark grey matrix is mammilary Arsenic.
 Viewed:  1407 Time(s)

IMG_8455.JPG


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Tobi




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PostPosted: Apr 16, 2017 10:50    Post subject: Re: Old St. Andreasberg specimen of Arsenic, Pyrargyrite and ?  

I'm not an expert on ore minerals from Harz, but the silvery stuff could indeed be arsenic, or maybe stibarsen ...? Not sure, sorry :-(
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GneissWare




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PostPosted: Apr 16, 2017 11:18    Post subject: Re: Old St. Andreasberg specimen of Arsenic, Pyrargyrite and ?  

Hi Tobi,
I was also thinking Arsenic, but generally the Arsenic turns dark-grey to black with time, whereas Stibarsen has a tin-white color. This seems more silvery.than the matrix, which is definitely Arsenic.
The red inclusions in the Quartz are intriguing.
Bob
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Joseph D'Oliveira




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PostPosted: Apr 16, 2017 11:55    Post subject: Re: Old St. Andreasberg specimen of Arsenic, Pyrargyrite and ?  

Hi Bob
could it be arsenopyrite as it usually has a whitish silver metallic luster?

GneissWare wrote:
Hi Tobi,
I was also thinking Arsenic, but generally the Arsenic turns dark-grey to black with time, whereas Stibarsen has a tin-white color. This seems more silvery.than the matrix, which is definitely Arsenic.
The red inclusions in the Quartz are intriguing.
Bob

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Jordi Fabre
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PostPosted: Apr 16, 2017 15:03    Post subject: Re: Old St. Andreasberg specimen of Arsenic, Pyrargyrite and ?  

Casually I recently ordered analysis of another specimen from St. Andreasberg with also unknown silvery gray material and it turned out to be Arsenopyrite.
Of course it don't means that your specimen should be the same, but without analysis I'm afraid that we can't do much more than adventure theories... ;-)
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GneissWare




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PostPosted: Apr 16, 2017 16:20    Post subject: Re: Old St. Andreasberg specimen of Arsenic, Pyrargyrite and ?  

Interesting Jordi. Arsenopyrite is listed as occurring, but the literature suggests it is not too prevalent. Perhaps, like many localities examined today by analytical techniques, many of the species thought to be uncommon are much more common!

Any ideas on the red inclusions in the Quartz? Ever seen hematite from here?
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