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Reef
Joined: 13 Dec 2016
Posts: 33
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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: 1498
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?
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1498
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 |
| Description: |
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264 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 |
| Description: |
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| Viewed: |
264 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 |
| Description: |
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| Viewed: |
265 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 |
| Description: |
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| Viewed: |
265 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 |
| Description: |
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| Viewed: |
264 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 |
| Description: |
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| Viewed: |
264 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: 19
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: 1498
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: 19
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: 600
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: 1498
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: 19
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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16 Time(s) |
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| Mineral: | q |
| Locality: | | Madagascar | |
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| Description: |
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| Viewed: |
16 Time(s) |
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| Mineral: | Quartz |
| Locality: | | Madagascar | |
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| Dimensions: | 9.2cm x10.8cm |
| Description: |
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| Viewed: |
16 Time(s) |
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| Description: |
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| Viewed: |
16 Time(s) |
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