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Enrique Llorens
Joined: 02 Jun 2011
Posts: 390
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Posted: Sep 09, 2016 09:42 Post subject: Re: Favourite Quartzes? |
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Quartz from Peru
Mineral: | Quartz |
Locality: | Mundo Nuevo mining area, Mundo Nuevo, Huamachuco, Sánchez Carrión Province, La Libertad Department, Peru | |
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Dimensions: | 11cm |
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22243 Time(s) |
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Michael Shaw
Site Admin
Joined: 30 Apr 2008
Posts: 2086
Location: Oklahoma
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Posted: Sep 09, 2016 10:34 Post subject: Re: Favourite Quartzes? |
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This tiny little Quartz var. Herkimer diamond has always been one of my favorites because of the clarity and unusual morphology. I collected this one back in 1962.
Mineral: | Quartz |
Locality: | Middleville, Town of Newport, Herkimer County, New York, USA | |
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Dimensions: | 8 mm x 10 mm |
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22167 Time(s) |
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geofossile
Joined: 29 Sep 2016
Posts: 10
Location: charleville mézières
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Posted: Sep 30, 2016 01:54 Post subject: Re: Favourite Quartzes? |
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Quartz with Muscovite (variety fuchsite) from Itremo, Madagascar.
Mineral: | Quartz with Muscovite (variety fuchsite) inclusions |
Locality: | Ihovitra, Itremo Massif, Itremo, Ambatofinandrahana District, Amoron'i Mania Region, Fianarantsoa Province, Madagascar | |
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22023 Time(s) |
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Jordi Fabre
Overall coordinator of the Forum
Joined: 07 Aug 2006
Posts: 4904
Location: Barcelona
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Posted: Sep 30, 2016 02:47 Post subject: Re: Favourite Quartzes? |
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geofossile wrote: | Quartz with Muscovite (variety fuchsite) from Itremo, Madagascar. |
Size please?
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Bergur_E_Sigurdarson
Joined: 21 Dec 2017
Posts: 147
Location: Paipa, Colombia
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Posted: Dec 25, 2017 08:04 Post subject: Re: Favourite Quartzes? |
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My favourite quartz, with paralell secondary growths.
Main crystal : H 85mm x W 27mm x D 25mm
Bought in the village of Muzo from local vendor.
(Can anyone tell me what this sort of growth would be called?)
(After looking for variations of quartz growths, the closest I could find was called "cactus", but those seemed to grow outwards from the main original crystal, not paralell like in this specimen.
Also, after reading another topic here on the forum, where photos of epitaxy were posted.... would this be an auto-epitaxy ?
(according to Pete Richards definition, if I understood correctly... but not according to John S. White (a discussion I enjoyed))) :-)
Mineral: | Quartz |
Locality: | Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia | |
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Dimensions: | H 8.5cm x W 4.6cm x D 3.7cm |
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20707 Time(s) |
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Mineral: | Quartz |
Locality: | Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia | |
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Dimensions: | H 8.5cm x W 4.6cm x D 3.7cm |
Description: |
Bottom view, showing opaque layer between initial and secondary growths. |
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vic rzonca
Joined: 18 Nov 2008
Posts: 820
Location: MA
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Posted: Dec 25, 2017 10:30 Post subject: Re: Favourite Quartzes? |
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This is from the book by Harold L. Dibble, Quartz." Cathedral Quartz. One of the most common of these types is known as Cathedral quartz. These are crystals with the axes of the secondary crystals parallel to those of the main crystal. These clusters vaguely resemble smaller spires or buttresses around the main spire of a cathedral." More of a descriptive term than a scientific one. I guess everything has to be called something.
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Tobi
Site Admin
Joined: 07 Apr 2009
Posts: 4112
Location: Germany
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Posted: Apr 08, 2018 13:09 Post subject: Re: Favourite Quartzes |
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Definitely two of my favourites:
Mineral: | Quartz (variety rock crystal) |
Locality: | Mount Ida, Montgomery County, Arkansas, USA | |
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Dimensions: | Specimen height 20,5 cm |
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19932 Time(s) |
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Mineral: | Quartz (variety smoky quartz) |
Locality: | Galiléia, Vale do Rio Doce, Minas Gerais, Brazil | |
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Dimensions: | Specimen height 14 cm |
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19950 Time(s) |
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Heimo Hellwig
Joined: 03 Aug 2014
Posts: 722
Location: Swakopmund
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Posted: Jun 03, 2018 11:45 Post subject: Re: Favourite Quartzes? |
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Quartz from Goboboseb. Saw this specimen when visiting an elderly gentleman in the retirement village. He allowed me to photograph and post it on the Forum. Nicest local Quartz I have come across.
Mineral: | Quartz |
Locality: | Goboboseb Mountains, Brandberg area, Erongo Region, Namibia | |
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Dimensions: | 112mm x 105mm x 68mm |
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19604 Time(s) |
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Mineral: | Quartz |
Locality: | Goboboseb Mountains, Brandberg area, Erongo Region, Namibia | |
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Dimensions: | 112mm x 105mm x 68mm |
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19661 Time(s) |
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Bob Harman
Joined: 06 Nov 2015
Posts: 765
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Posted: Jun 05, 2018 09:54 Post subject: Re: Favourite Quartzes? |
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Groups of tiny water clear quartz crystals showing free form growths adjacent to a calcite crystal. Self collected about 10 years ago.
Mineral: | QUARTZ |
Locality: | Monroe County, Indiana, USA | |
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Dimensions: | The individual crystals are 1 - 3mm. The whole area is about 2.5 cm |
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Self collected about 10 years ago. |
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19481 Time(s) |
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Mineral: | Quartz |
Locality: | Monroe County, Indiana, USA | |
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Dimensions: | The individual crystals are 1 - 3mm. The whole area is about 2.5 cm |
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19498 Time(s) |
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Tobi
Site Admin
Joined: 07 Apr 2009
Posts: 4112
Location: Germany
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Posted: Jun 10, 2018 00:40 Post subject: Re: Favourite Quartzes? |
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Heimo Hellwig wrote: | Quartz from Goboboseb. Saw this specimen when visiting an elderly gentleman in the retirement village. He allowed me to photograph and post it on the Forum. Nicest local Quartz I have come across.
Locality: Goboboseb Mountains, Brandberg area, Erongo Region, Namibia
Dimensions: 112mm x 105mm x 68mm | This is really one of the most fascinating Brandberg quartzes I have ever seen, Heimo, thanks for showing!
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James Catmur
Site Admin
Joined: 14 Sep 2006
Posts: 1351
Location: Cambridge
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Posted: Jun 13, 2018 14:12 Post subject: Re: Favourite Quartzes? |
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This seems to be an open Gwindel from Spain. We found this single specimen in 2007 in a small outcrop next to a vein of quartz. There were other quartz crystals but none like this. The crystal faces are parallel but there is a slight twist between the two crystals, which I only noticed today.
See what you think? Is it a Gwindel or just two almost totally parallel crystals
The locality where it was found is mentioned in Volumen VIII, Cuarzo y otros minerales de silice, Miguel Calvo Rebollar, p 243, top of the page where it says "La Presa".
Mineral: | Quartz |
Locality: | "The Dam", Aulencia River, Colmenarejo, Comarca Cuenca del Guadarrama, Community of Madrid, Spain | |
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Dimensions: | 53 x 25 x 15 mm |
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Mineral: | Quartz |
Locality: | "The Dam", Aulencia River, Colmenarejo, Comarca Cuenca del Guadarrama, Community of Madrid, Spain | |
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Dimensions: | 53 x 25 x 15 mm |
Description: |
You can see the twist in this one |
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Mineral: | Quartz |
Locality: | "The Dam", Aulencia River, Colmenarejo, Comarca Cuenca del Guadarrama, Community of Madrid, Spain | |
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Dimensions: | 53 x 25 x 15 mm |
Description: |
And the parallel faces in this one. |
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19188 Time(s) |
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Bob Morgan
Joined: 18 Jan 2018
Posts: 229
Location: Savannah, Georgia
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Bob Morgan
Joined: 18 Jan 2018
Posts: 229
Location: Savannah, Georgia
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Posted: Jun 13, 2018 20:14 Post subject: Re: Favourite Quartzes? |
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The above post was in reference to Enrique LLorenz's Peruvian Specimen at the first of this thread.
https://www.mineral-forum.com/message-board/download.php?id=72376
As to the question about whether the double crystal immediately above is a Gwindel, I don't think so. The attachment would be on a prism face.
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James Catmur
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Joined: 14 Sep 2006
Posts: 1351
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Posted: Jun 14, 2018 08:13 Post subject: Re: Favourite Quartzes? |
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Bob
The attachment is a prism face - the two are attached to each other by their prism faces. That is why it had me confused - every face in each crystal has a parallel face in the other one, but there is about a 4 degree twist between them. So it looks like two totally parallel crystsls with a twist (clockwise) between them.
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Bob Morgan
Joined: 18 Jan 2018
Posts: 229
Location: Savannah, Georgia
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Posted: Jun 14, 2018 08:45 Post subject: Re: Favourite Quartzes? |
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I can see your point and agree the divergence is reasonable as a gwindel. I was referring to the attachment to the matrix, which is usually along a prism face of one crystal. Still...?
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Josele
Joined: 10 Apr 2012
Posts: 410
Location: Tarifa, Spain
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Posted: Jun 14, 2018 15:47 Post subject: Re: Favourite Quartzes? |
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Bob Morgan wrote: | ... As to the question about whether the double crystal immediately above is a Gwindel, I don't think so. The attachment would be on a prism face. | I think is not a gwindel precisely because the attachment IS on prism faces. Should be on a "a" axis, which cross an edge between two prism faces. Gwindel rotation occurs along this "a" axis and the result is a wide prism face with steps that are a progresively rotated. Is really better explained in The Quartz Bible.
Japan law twin has the contact plane almost on the bisector of "c" and a "a" axis, so that "c" axis of both crystals cross in one point conforming an almost right angle and leaving two of the prism faces of one individual parallel to two prism faces of the other, which I'm not able to observe in the picture. Again, is better explained in The Quartz Bible.
Bob Morgan wrote: | I can see your point and agree the divergence is reasonable as a gwindel. I was referring to the attachment to the matrix, which is usually along a prism face of one crystal. Still...? | The attachment to matrix is irrelevant, I think.
Anyway, I don't see any matrix in James's quartz, seems to be an almost floater piece.
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Bob Morgan
Joined: 18 Jan 2018
Posts: 229
Location: Savannah, Georgia
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Posted: Jun 14, 2018 17:41 Post subject: Re: Favourite Quartzes? |
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I agree it's not a gwindel, even though it looks like there might be an a axis alignment at some spot. Very open gwindels can have some notched separation, but this would be too extreme.
There does appear to be a point of attachment on one crysrtal's pyramid, but gwindels grow out of the matrix along the a axis.
As to the Peruvian quartz, the possible twinning would be small deposition crystals on larger ones. That is very common from that locality, but can't be discerned from the photo.
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Josele
Joined: 10 Apr 2012
Posts: 410
Location: Tarifa, Spain
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Posted: Jun 14, 2018 18:00 Post subject: Re: Favourite Quartzes? |
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Bob, you are right, many characteristics are not clearly visible in a photo, that's why I like to say "I think that ..."
Is true that high end and fine gwindel specimens usually show both terminations free of contact, with "c" axis more or less parallel to matrix surface, but there are also many samples that seem to be attached to matrix at terminations, with "c" axis penetrating into matrix, as can be seen in Gwindel Mindat Gallery
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Amir Akhavan
Joined: 01 Dec 2009
Posts: 95
Location: Hamburg
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Posted: Jun 15, 2018 05:26 Post subject: Re: Favourite Quartzes? |
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Sorry to interrupt ;-) but I'd like to point out that a gwindel is not a composite or aggregate.
It's not made of stacked crystals and it has nothing to do with parallel growth.
Each gwindel started as a s i n g l e c r y s t a l that is elongated along and twisted around an a-axis.
That many gwindels and in particular open gwindels show sutures and that their tips fan out is a secondary effect of being overgrown by a layer of macromosaic quartz.
Amir
_________________ Amir C. Akhavan, Hamburg, Germany |
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Tobi
Site Admin
Joined: 07 Apr 2009
Posts: 4112
Location: Germany
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Posted: Oct 28, 2018 06:52 Post subject: Re: Favourite Quartzes? |
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A few more of my personal favourites from my collection that I want to add:
Mineral: | Quartz |
Locality: | Itremo Massif, Itremo, Ambatofinandrahana District, Amoron'i Mania Region, Fianarantsoa Province, Madagascar | |
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Dimensions: | Specimen height 9,5 cm |
Description: |
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Viewed: |
16773 Time(s) |
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Mineral: | Smoky Quartz |
Locality: | Erongo Mountain, Usakos, Erongo Region, Namibia | |
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Dimensions: | Specimen height 13 cm |
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Viewed: |
16763 Time(s) |
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Mineral: | Quartz |
Locality: | Huanggang Mines, Hexigten Banner (Kèshíkèténg Qí), Chifeng (Ulanhad), Inner Mongolia Autonomous Region, China | |
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Dimensions: | Specimen height 11 cm |
Description: |
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16768 Time(s) |
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Mineral: | Quartz |
Locality: | Dalnegorsk, Dalnegorsk Urban District, Primorsky Krai, Russia | |
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Dimensions: | Specimen height 14 cm |
Description: |
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16774 Time(s) |
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