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Goethite
  
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Mathias




Joined: 01 Apr 2018
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PostPosted: Mar 08, 2020 12:39    Post subject: Goethite  

Dear Friends of Minerals,

A few months ago, I purchased a specimen with the following Label:

Goethite, Herdorf, Germany.

The specimen is heavy (4 kilo), 18 x 12 cm.
I can't find a similar specimen on Mindat.
The specimen has a layered structure and layers are approximately 1 cm thick.

Has anybody ever encountered a similar specimen before?
How does this structure form?

Thanks,
Mathias



601I.JPG
 Mineral: Goethite
 Dimensions: 18 cm x 12 (cm)
 Description:
 Viewed:  1396 Time(s)

601I.JPG



601B.JPG
 Description:
 Viewed:  1392 Time(s)

601B.JPG



601E.JPG
 Description:
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601E.JPG


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Tobi




Joined: 07 Apr 2009
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Location: Good Old Germany


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PostPosted: Mar 09, 2020 06:12    Post subject: Re: Goethite  

Hi Mathias,

Herdorf is not one single locality but a mining area with several mines, the most famous is for sure Wolf Mine where the legendary rhodochrosites come from. I don't know for sure if this specimen is from that area but iron minerals like goethite or limonite are common there in different shapes so maybe the information is correct, not sure.

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Tobi
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Matt_Zukowski
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PostPosted: Mar 09, 2020 17:12    Post subject: Re: Goethite  

It looks like petrified wood. Any possibility it is wood replaced in part by Fe/Mn oxides/hydroxides?
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Roger Warin




Joined: 23 Jan 2013
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PostPosted: Mar 09, 2020 17:31    Post subject: Re: Goethite  

The needle crystals are vertically associated and form layers of successive deposits.
In addition, the wood does not contain horizontal interruptions.
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