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Inclusions of spiral or helical growth and screw dislocations - (0)
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Elise




Joined: 22 Dec 2009
Posts: 243
Location: New York State


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PostPosted: Dec 17, 2015 14:51    Post subject: Re: Inclusions of spiral or helical growth and screw dislocations - (0)  

Look what's on the 2016 15th Annual Westward Look Mineral Show poster - it features a 49-mm-tall heliodor crystal from the Yellow Water Mine in Tajikistan; photographed by Joe Budd (shared with permission from Dave Waisman)!


2016_Westward_Look_Show_Joe_Budd_photo.jpg
 Description:
15th Annual Westward Look Mineral Show poster. Photo: Joe Budd
 Viewed:  4500 Time(s)

2016_Westward_Look_Show_Joe_Budd_photo.jpg



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Elise Skalwold
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Sante Celiberti




Joined: 04 Oct 2019
Posts: 132
Location: Tuscany


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PostPosted: Nov 11, 2019 15:46    Post subject: Re: Inclusions of spiral or helical growth and screw dislocations - (0)  

Hello.

I have in my quartz sub-collection two small crystals, coming from the same locality, with a curious inclusion that resembles the screw dislocation.

The first one shows a tunnel with a geometrical "repetitive" pattern. Surprisingly the tunnel is open on both sides. I guess it is a sort of etching/dissolution that interested the included mineral (probably Siderite, which is often associated with Quartz from this locality).

The second one shows a small inclusion of possible Siderite with the same repetitive screw pattern, which needs to be magnified.

I would like to know the experts opinion.
Thanks in advance.
Best regards.
Sante



IMG_20191110_190920.jpg
 Mineral: Quartz
 Locality:
Leoni Mountain, Sticciano, Roccastrada, Grosseto Province, Tuscany, Italy
 Dimensions: 15,66 x 13,85 x 8 mm
 Description:
Front view. The crystal has grown on C axis and the pattern is parallel to it.
 Viewed:  2231 Time(s)

IMG_20191110_190920.jpg



IMG_20191110_191358.jpg
 Mineral: Quartz
 Locality:
Leoni Mountain, Sticciano, Roccastrada, Grosseto Province, Tuscany, Italy
 Dimensions: 15,66 x 13,85 x 8 mm
 Description:
Back view.
 Viewed:  2226 Time(s)

IMG_20191110_191358.jpg



IMG_20191110_185423.jpg
 Mineral: Quartz
 Locality:
Leoni Mountain, Sticciano, Roccastrada, Grosseto Province, Tuscany, Italy
 Dimensions: 15,66 x 13,85 x 8 mm
 Description:
The tunnel is open on both sides.
 Viewed:  2228 Time(s)

IMG_20191110_185423.jpg



IMG_20191111_174237.jpg
 Mineral: Quartz, Siderite
 Locality:
Leoni Mountain, Sticciano, Roccastrada, Grosseto Province, Tuscany, Italy
 Dimensions: 20 x 14 x 5 mm
 Description:
The crystal has grown on A axis.The possible Siderite inclusion with screw pattern is neither parallel to the A axis nor to the C axis.
 Viewed:  2238 Time(s)

IMG_20191111_174237.jpg


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Sante Celiberti




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PostPosted: Dec 21, 2019 17:44    Post subject: Re: Inclusions of spiral or helical growth and screw dislocations - (0)  

Hello.

Sorry, in the first picture's description of my previous post I erroneously wrote "parallel" instead of "perpendicular".

In this thread Mr. Duncan Miller said in 2011: "...so far I have not seen any images of these helical inclusions in quartz."; and Mr. Marco Campos-Venuti showed us, in 2014, his very beautiful quartz from Brasil.
Five years later I'd like to know the experts opinion about the attached specimens.

The first one is a Brasilian chalcedony geode. Looking for a nice goethite tuft in chalcedony, 15 years ago I came across this piece which at first sight I exchanged for faden quartz. Once at home, on closer inspection I realized that what I thought was a string was actually a spiral-shaped inclusion.

What attracted me to the small Chinese quartz was its strong iridescence due to internal fractures. Only later I noticed the small spiral-shaped inclusion inside it.

The third specimen is a Tuscan stalactitic chalcedony with a curious screw-formation. Also Mr. Campos-Venuti showed one. Has it anything to do with the helical-inclusion/dislocation theme?

Has knowledge of this intriguing topic progressed in recent years, just as Ms. Elise gave hope?

My best regards and wishes for coming holidays to all of you.
Sante



48,8 x 38,2.jpg
 Mineral: Quartz (variety chalcedony), Quartz
 Locality:
Barros Cassal, Rio Grande do Sul, Brazil
 Dimensions: 48,8 x 38,2 mm
 Description:
Both terminations of quartz crystal are attached to the walls of the geode.
 Viewed:  1991 Time(s)

48,8 x 38,2.jpg



IMG_20191219_110405.jpg
 Mineral: Quartz (variety chalcedony), Quartz
 Locality:
Barros Cassal, Rio Grande do Sul, Brazil
 Dimensions: 48,8 x 38,2 mm
 Description:
A close up of spiral-shaped inclusion. What kind of inclusion? It looks very similar to "flakes" on polished surface of chalcedony. Might it be crystobalite (quartz after crystobalite)?
 Viewed:  1992 Time(s)

IMG_20191219_110405.jpg



IMG_20191219_105315.jpg
 Mineral: Quartz (variety chalcedony), Quartz
 Locality:
Barros Cassal, Rio Grande do Sul, Brazil
 Dimensions: 48,8 x 38,2 mm
 Description:
Other view of spiral-shaped iclusion. Can we call it "helical" inclusion?
 Viewed:  1988 Time(s)

IMG_20191219_105315.jpg



IMG_20191219_113250.jpg
 Mineral: Quartz (variety smoky and variety scepter)
 Locality:
Leshan Prefecture, Sichuan Province, China
 Dimensions: 18 x 12 mm
 Description:
Front view where you can see a screw-shaped small inclusion.
 Viewed:  1987 Time(s)

IMG_20191219_113250.jpg



IMG_20191219_115423.jpg
 Mineral: Quartz (variety smoky and variety scepter)
 Locality:
Leshan Prefecture, Sichuan Province, China
 Dimensions: 18 x 12 mm
 Description:
Side view where you can see the spiral-shaped inclusion. Is it actually an inclusion or a "large scale" helical dislocation?
 Viewed:  1986 Time(s)

IMG_20191219_115423.jpg



IMG_20191221_115216.jpg
 Mineral: Quartz (variety chalcedony), Quartz
 Locality:
Monterufoli, Pomarance, Pisa Province, Tuscany, Italy
 Dimensions: 114 x 105 mm
 Description:
The Chalcedony stalactite size is 60 mm.
 Viewed:  1986 Time(s)

IMG_20191221_115216.jpg



IMG_20191221_121229.jpg
 Mineral: Quartz (variety chalcedony), Quartz
 Locality:
Monterufoli, Pomarance, Pisa Province, Tuscany, Italy
 Dimensions: 114 x 105 mm
 Description:
Close up of the spiral-shaped formation. Pure randomness or we can suspect a relation with the helical (dis)location?
 Viewed:  1989 Time(s)

IMG_20191221_121229.jpg


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