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Jordi Fabre
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Joined: 07 Aug 2006
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Location: Barcelona
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 Posted: Sep 25, 2012 15:07 Post subject: Re: Strange Quartz found In New York |
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| J. Lawsonite wrote: | | ....it is another iron oxide of some sort e.g. goethite. |
I agree, I would vote for Goethite.
Adam, could you check if the color of the needles changes according its position from black to yellowish-brown? The Goethite is pleochroic....
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Pete Richards
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| Posted: Sep 25, 2012 15:51 Post subject: Re: Strange Quartz found In New York |
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| J. Lawsonite wrote: | | I have a strong feeling that the "fibrous" mineral inclusion that you see is hematite, less likely but still possible. it is another iron oxide of some sort e.g. goethite. |
I've never heard of fibrous hematite. Hematite usually forms platy pseudo-hexagonal crystals, or botryoidal masses composed of gazillions of crystals all packed together. But not separate fibers.
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Jordi Fabre
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| Posted: Sep 25, 2012 16:11 Post subject: Re: Strange Quartz found In New York |
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Two examples of needles / sprays of Goethite inside Quartz from Morocco
| Description: |
Quartz with Goethite
Tizirine, Tizi n'Tichka, Ouarzazate Morocco
Main crystal size: 1.8 × 1.3 cm. |
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13641 Time(s) |
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| Description: |
Quartz with Goethite
Tizirine, Tizi n'Tichka, Ouarzazate Morocco
Main crystal size: 1.8 × 1.3 cm. |
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| Viewed: |
13613 Time(s) |
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Carl
Joined: 07 May 2009
Posts: 28
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| Posted: Sep 26, 2012 21:41 Post subject: Re: Strange Quartz found In New York |
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The analysis that NYSAM did back in the late 1990s on this material was that it was an amphibole; likely riebeckite. I have several pieces where the amphibole crystals go from one quartz crystal, through open space, and into another quartz crystal.
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