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Reef
Joined: 13 Dec 2016
Posts: 36
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 Posted: Oct 19, 2017 15:20 Post subject: Re: Weird face in quartz |
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With your permission, I will continue to display rare quartz faces
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37544 Time(s) |
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37571 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia |  |
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| Dimensions: | 20x10mm |
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| face of a rhombohedron (012) |
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37551 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Dimensions: | 23x12mm |
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| face of a rhombohedron (012) |
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37530 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Dimensions: | 23x12mm |
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| face of a rhombohedron (012) |
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37532 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Dimensions: | 23x12mm |
| Description: |
| face of a rhombohedron (012) |
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37591 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Dimensions: | 17x16mm |
| Description: |
| face of a rhombohedron (012) |
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37571 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Dimensions: | 17x16mm |
| Description: |
| face of a rhombohedron (012) |
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37602 Time(s) |
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Reef
Joined: 13 Dec 2016
Posts: 36
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| Posted: Oct 20, 2017 09:57 Post subject: Re: Weird face in quartz |
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Sometimes a rhombohedron (012) is replaced by a ditrigonal scalenohedron. Together with {012}, on the vertex there are occasional faces from (103) to (1.0.11), down to the pinacoid (001).
| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Dimensions: | 23x17mm |
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37511 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Dimensions: | 23x17mm |
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37494 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Dimensions: | 23x17mm |
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37543 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Here, the more noticeable is the ditrigonal skalenohedron |
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37498 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Orenburgskaya Oblast, Southern Urals, Urals Region, Russia | |
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| Description: |
| Here, the more noticeable is the ditrigonal skalenohedron |
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37544 Time(s) |
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37518 Time(s) |
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marco campos-venuti
Joined: 09 Apr 2014
Posts: 234
Location: Sevilla
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| Posted: Oct 20, 2017 11:20 Post subject: Re: Weird face in quartz |
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| Hi Reef, do you think these faces are originated by dissolution (etching)? They remember the "Quarzi Gommoidi" of Luigi Bombicci from Colle Palombaia, Elba Island. He refers to a finding of quartz crystals in '800 with rounded termination due to many tiny faces on the top of the crystals.
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Reef
Joined: 13 Dec 2016
Posts: 36
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| Posted: Oct 20, 2017 12:34 Post subject: Re: Weird face in quartz |
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| marco campos-venuti wrote: | | Hi Reef, do you think these faces are originated by dissolution (etching)? They remember the "Quarzi Gommoidi" of Luigi Bombicci from Colle Palombaia, Elba Island. He refers to a finding of quartz crystals in '800 with rounded termination due to many tiny faces on the top of the crystals. |
Hi, marco campos-venuti. As far as I can tell, it's all growth faces. At this deposit quartz with inclusions of oil, lamellar structure. Basically skeletal, i.e. growth occurred rapidly and at relatively low crystallization temperatures. On some veins, there are single samples similar to dissolution, but I think this kind is due to rapid growth.
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Nov 15, 2017 10:23 Post subject: Re: Weird face in quartz |
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Here is another specimen with an interesting face. I cannot remember ever seeing anything similar to this. I drew a yellow arrow to indicate the area of interest.
| Mineral: | Quartz, variety amethyst |
| Locality: | | Goboboseb Mountains, Brandberg area, Erongo Region, Namibia | |
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| Dimensions: | 33 x 25 x 20 mm |
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36885 Time(s) |
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| A pencil sketch of the specimen. |
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36866 Time(s) |
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| Mineral: | Quartz, variety amethyst |
| Locality: | | Goboboseb Mountains, Brandberg area, Erongo Region, Namibia | |
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| Dimensions: | 33 x 25 x 20 mm |
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36921 Time(s) |
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_________________
Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Reef
Joined: 13 Dec 2016
Posts: 36
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| Posted: Nov 15, 2017 11:10 Post subject: Re: Weird face in quartz |
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| Hello, Pierre! On your photo, a parallel splice, at least 3 crystals. You see a rhombohedron of the third crystal. Such composite crystals an everyday occurrence.
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Nov 15, 2017 12:55 Post subject: Re: Weird face in quartz |
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| Reef wrote: | | Hello, Pierre! On your photo, a parallel splice, at least 3 crystals. You see a rhombohedron of the third crystal. Such composite crystals an everyday occurrence. |
Do you mind showing me something similar?
_________________
Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Aug 09, 2018 13:52 Post subject: Re: Weird face in quartz |
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Here is yet another unusual specimen that I found a few weeks ago. One side has a curved face all the way from the bottom to the termination point. I have never seen anything like it. I would appreciate it if anyone can shed some light on this mysterious occurrence.
| Mineral: | Quartz (variety smoky) |
| Locality: | | Villiersdorp, Theewaterskloof, Overberg, Western Cape, South Africa | |
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| Dimensions: | 88 x 40 x 29 mm |
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15546 Time(s) |
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| Mineral: | Quartz (variety smoky) |
| Locality: | | Villiersdorp, Theewaterskloof, Overberg, Western Cape, South Africa | |
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| Dimensions: | 88 x 40 x 29 mm |
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15540 Time(s) |
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| Mineral: | Quartz (variety smoky) |
| Locality: | | Villiersdorp, Theewaterskloof, Overberg, Western Cape, South Africa | |
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| Dimensions: | 88 x 40 x 29 mm |
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15531 Time(s) |
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| Mineral: | Quartz (variety smoky) |
| Locality: | | Villiersdorp, Theewaterskloof, Overberg, Western Cape, South Africa | |
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| Dimensions: | 88 x 40 x 29 mm |
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15525 Time(s) |
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| Mineral: | Quartz (variety smoky) |
| Locality: | | Villiersdorp, Theewaterskloof, Overberg, Western Cape, South Africa | |
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| Dimensions: | 88 x 40 x 29 mm |
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15538 Time(s) |
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| Mineral: | Quartz (variety smoky) |
| Locality: | | Villiersdorp, Theewaterskloof, Overberg, Western Cape, South Africa | |
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| Dimensions: | 88 x 40 x 29 mm |
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15545 Time(s) |
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Bob Morgan
Joined: 18 Jan 2018
Posts: 251
Location: Savannah, Georgia
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| Posted: Aug 09, 2018 21:17 Post subject: Re: Weird face in quartz |
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Amen to your question. I have a similarly bent quartz that came with the only identifier of locality as Madagascar.
It isn't like a gwindel - bent in different direction. The surface is smooth and almost waxy.
I look forward to the explanations!
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Aug 10, 2018 02:37 Post subject: Re: Weird face in quartz |
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| Bob Morgan wrote: | Amen to your question. I have a similarly bent quartz that came with the only identifier of locality as Madagascar.
It isn't like a gwindle - bent in different direction. The surface is smooth and almost waxy.
I look forward to the explanations! |
Hi Bob. This crystal is not bent at all. The 'curve' is slightly twisted and runs the length of the crystal. Looking forward to seeing your specimen.
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Bob Morgan
Joined: 18 Jan 2018
Posts: 251
Location: Savannah, Georgia
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| Posted: Aug 10, 2018 14:53 Post subject: Re: Weird face in quartz |
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| I should have said the face is curved. My specimen isn't bent either, another distinction from Gwindels.
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Pete Richards
Site Admin
Joined: 29 Dec 2008
Posts: 846
Location: Northeast Ohio
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| Posted: Aug 13, 2018 13:34 Post subject: Re: Weird face in quartz |
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| Pierre Joubert wrote: | | Here is yet another unusual specimen that I found a few weeks ago. One side has a curved face all the way from the bottom to the termination point. I have never seen anything like it. I would appreciate it if anyone can shed some light on this mysterious occurrence. |
I observe that the crystal appears to be fractured in several places. I wonder if the curved surface could be a large conchoidal fracture that removed that portion of the crystal. Perhaps there was a little secondary growth or etching, or perhaps not. I know this is not a very exciting proposal, but quartz IS known for its conchoidal fracture.
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Collecting and studying crystals with interesting habits, twinning, and epitaxy |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Aug 13, 2018 14:38 Post subject: Re: Weird face in quartz |
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| Pete Richards wrote: | | Pierre Joubert wrote: | | Here is yet another unusual specimen that I found a few weeks ago. One side has a curved face all the way from the bottom to the termination point. I have never seen anything like it. I would appreciate it if anyone can shed some light on this mysterious occurrence. |
I observe that the crystal appears to be fractured in several places. I wonder if the curved surface could be a large conchoidal fracture that removed that portion of the crystal. Perhaps there was a little secondary growth or etching, or perhaps not. I know this is not a very exciting proposal, but quartz IS known for its conchoidal fracture. |
Hi Pete. Thank you for your input. The 'curve' is much too consistent for a fracture (I suppose it is not impossible). There is a black unknown mineral that has formed with the crystals in this pocket. The black mineral is included in many of the crystals and in many cases, weathered away leaving deep 'channels' in the crystals. I will attempt to show photos of this strange occurrence soon. This is indeed a strange find. Perhaps the black mineral somehow contributed to the formation of this strange curve.
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Bob Morgan
Joined: 18 Jan 2018
Posts: 251
Location: Savannah, Georgia
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| Posted: Aug 14, 2018 15:05 Post subject: Re: Weird face in quartz |
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Here're pics of my curve faced quartz, Every terminal face is curved though two are radically so. There are some curved patches of prism faces also. On one corner where 's' and 'x' faces might appear there is a appropriately shaped structure that stands out as if less effected by etching that might cause the other curved faces. The one pyramidal face with triangular hillocks has slightly different orientations - the top being different from the bottom pyramid faces. This also seems to show signs of c-axis twinning to help account for this.
| Locality: | | Madagascar | |
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15314 Time(s) |
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| Mineral: | q |
| Locality: | | Madagascar | |
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15368 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Madagascar | |
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| Dimensions: | 9.2cm x10.8cm |
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15357 Time(s) |
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15306 Time(s) |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Aug 15, 2018 05:51 Post subject: Re: Weird face in quartz |
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Hi Bob. Very interesting! P8140016 (3).JPG
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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