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John Jaszczak
Joined: 05 Oct 2010
Posts: 300
Location: Hancock, MI
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 Posted: Nov 05, 2016 13:03 Post subject: Merelaniite - a new mineral from the famous tanzanite deposit |
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Following keen observations by Jessica Simonoff, Robert Simonoff, and Mike Wise of unusual black whiskers associated with other minerals from the tanzanite mines near Merelani, Tanzania, Jessica and Mike published their observations in Mineral News in 2012, with a preliminary identification of the whiskers as molybdenite. Subsequent investigations of these whiskers, which form scroll-like structures similar to cylindrite, showed that they were indeed a cylindrite-group mineral with alternating layers of MoS2 and PbS rich chemistry. The new mineral (IMA 2016-042) is called merelaniite, after the locality and in honor of the miners who work there. For more information see the open access article in Minerals:
https://www.mdpi.com/2075-163X/6/4/115
| Mineral: | Merelaniite |
| Locality: | | Merelani mines, Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania |  |
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| Dimensions: | 0.73 mm |
| Description: |
| 0.73-mm cylindrical whisker associated with Tremolite and Prehnite.http://www.mdpi.com/2075-163X/6/4/115 |
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| Viewed: |
20031 Time(s) |
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| Mineral: | Merelaniite in Quartz |
| Locality: | | Merelani mines, Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania | |
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| Dimensions: | 2.8 cm tall |
| Description: |
| Merelaniite whiskers in quartz, associated with chabazite. A. E. Seaman Mineral Museum specimen. ex Simon Harrison. http://www.mdpi.com/2075-163X/6/4/115 |
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| Viewed: |
20024 Time(s) |
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| Mineral: | Merelaniite |
| Locality: | | Merelani mines, Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania | |
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| Dimensions: | ~5 nm scale bar |
| Description: |
| High Resolution Transmission Electron Microscope image of a fragment of merelaniite showing the alternating layers (along the radial direction of the cylindrical whisker).http(:)//www(.)mdpi(.)com/2075-163X/6/4/115 |
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| Viewed: |
20046 Time(s) |
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Adjunct Curator, A. E. Seaman Mineral Museum
Professor of Physics
Michigan Technological University |
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Jordi Fabre
Overall coordinator of the Forum
Joined: 07 Aug 2006
Posts: 5025
Location: Barcelona
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| Posted: Nov 05, 2016 13:21 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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| Warmest congratulations John!
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John Jaszczak
Joined: 05 Oct 2010
Posts: 300
Location: Hancock, MI
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| Posted: Nov 05, 2016 21:34 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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Scanning electron microscope image of a merelaniite whisker showing the termination and also some variation in the diameter (about 24 microns maximum). (Piece of the holotype specimen.)
| Mineral: | Merelaniite |
| Locality: | | Merelani mines, Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania | |
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| Dimensions: | 24 microns max diameter |
| Description: |
| Merelaniite whisker found in a crevice of a large alabandite crystal. |
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| Viewed: |
19892 Time(s) |
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_________________
Adjunct Curator, A. E. Seaman Mineral Museum
Professor of Physics
Michigan Technological University |
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John Jaszczak
Joined: 05 Oct 2010
Posts: 300
Location: Hancock, MI
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| Posted: Nov 07, 2016 16:03 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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SEM image of a 12-micron diameter broken whisker revealing the coiled nature of its layered structure.
| Mineral: | Merelaniite |
| Locality: | | Merelani mines, Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania | |
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| Dimensions: | 12-micron diameter |
| Description: |
| Broken merelaniite structure showing its layered texture. |
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| Viewed: |
19611 Time(s) |
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_________________
Adjunct Curator, A. E. Seaman Mineral Museum
Professor of Physics
Michigan Technological University |
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John Jaszczak
Joined: 05 Oct 2010
Posts: 300
Location: Hancock, MI
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| Posted: Nov 10, 2016 14:51 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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Very interesting and unusually large merelaniite whisker that has some layers naturally unwound and encased in calcite (white). The overall whisker is about 5 mm long.
| Mineral: | Merelaniite |
| Locality: | | Merelani mines, Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania | |
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| Dimensions: | 5 mm (largest whisker) |
| Description: |
| Merelaniite with calcite and prehnite. |
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| Viewed: |
19518 Time(s) |
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_________________
Adjunct Curator, A. E. Seaman Mineral Museum
Professor of Physics
Michigan Technological University |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1232
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| Posted: Nov 11, 2016 05:47 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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Merelianiite
Thank you for this beautiful info. There are no limits to the mineral world.
Just open the eyes of the new machines.
The Malagasy deposits are also full of hope.
Roger.
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John Jaszczak
Joined: 05 Oct 2010
Posts: 300
Location: Hancock, MI
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| Posted: Nov 13, 2016 17:02 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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Close up of the above specimen showing the partly-exposed whisker of merelaniite.
| Mineral: | Merelaniite |
| Locality: | | Merelani mines, Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania | |
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| Dimensions: | 1.43-mm wide field of view |
| Description: |
| close up showing naturally "unwound" layers partly encased in clear calcite. |
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| Viewed: |
19358 Time(s) |
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_________________
Adjunct Curator, A. E. Seaman Mineral Museum
Professor of Physics
Michigan Technological University |
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John S. White
Site Admin
Joined: 04 Sep 2006
Posts: 1298
Location: Stewartstown, Pennsylvania, USA
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| Posted: Nov 13, 2016 20:58 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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So what is the composition of merelaniite?
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John S. White
aka Rondinaire |
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John Jaszczak
Joined: 05 Oct 2010
Posts: 300
Location: Hancock, MI
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| Posted: Nov 13, 2016 22:42 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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Hi John
The microprobe analyses give
Mo4.33 Pb4.00 As0.10 V0.86 Sb0.43 Bi0.33 Mn0.05 W0.05 Cu0.03 (S14.70 Se0.30)_Sum=15
or more simply, Mo4 Pb4 V Sb S15
but it is an incommensurate structure so this is just approximate. There is also an As rich variety that at least for now, we don't believe is a new species, but more work needs to be done.
_________________
Adjunct Curator, A. E. Seaman Mineral Museum
Professor of Physics
Michigan Technological University |
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John Jaszczak
Joined: 05 Oct 2010
Posts: 300
Location: Hancock, MI
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| Posted: Nov 26, 2016 13:30 Post subject: Re: Merelaniite - a new mineral from the famous tanzanite deposit |
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Merelaniite whisker showing pronounced variation along its axis of its diameter. Partially protruding from calcite.
| Mineral: | Merelaniite |
| Locality: | | Merelani mines, Merelani Hills, Lelatema Mountains, Simanjiro District, Manyara Region, Tanzania | |
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| Dimensions: | 0.9 mm |
| Description: |
| whisker of merelaniite with calcite (and prehnite, not shown) |
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| Viewed: |
19046 Time(s) |
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_________________
Adjunct Curator, A. E. Seaman Mineral Museum
Professor of Physics
Michigan Technological University |
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