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How quartz crystals are formed.
  
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Pierre Joubert




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PostPosted: Aug 11, 2013 06:14    Post subject: How quartz crystals are formed.  

For those who do not quite understand the way quartz crystals grow in nature, here are a few sources of information that would hopefully help to better understand this mystery. Man has imitated nature and thereby given us a glimpse of how nature produces it's gems.















https://www.quartzpage.de
(link normalized by FMF)

I would welcome it if If anyone else has anything of interest to add to this thread.



100_2144.JPG
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Quartz
Western Cape, South Africa
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Carles Millan
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PostPosted: Aug 11, 2013 09:12    Post subject: Re: How quartz crystals are formed.  

Hi Pierre,

The very short answer to the question How quartz crystals are formed is that most of them grow from an aqueous solution. Overheated water, up to 647K (374 Celsius) at a very high pressure (22 MPa or 218 atm can be needed), getting cooler or evaporating while circulating inside a cleft. Perhaps the second most frequent process is from a cooling magma like granite or pegmatite. An exciting topic that may well deserve a deeper aproach.
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Pierre Joubert




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PostPosted: Aug 11, 2013 12:32    Post subject: Re: How quartz crystals are formed.  

Carles Millan wrote:
Hi Pierre,

The very short answer to the question How quartz crystals are formed is that most of them grow from an aqueous solution. Overheated water, up to 647K (374 Celsius) at a very high pressure (22 MPa or 218 atm can be needed), getting cooler or evaporating while circulating inside a cleft. Perhaps the second most frequent process is from a cooling magma like granite or pegmatite. An exciting topic that may well deserve a deeper aproach.


Hi Carles. Thank you for simplifying it. I find it surprising how many people we meet actually don't know this. A number of people who see our crystals ask us who cut them like that.

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Mark Ost




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PostPosted: Aug 11, 2013 12:50    Post subject: Re: How quartz crystals are formed.  

That actually is a very reasonable assumption. If you think about it, nature almost never works in straight lines and the perfection of fine minerals surely does look man or machine made. An interesting story about straight lines:

Colorblind people often were used, years ago, in intelligence and aerial photo work because what they lacked in color perception was often made up in being very sensitive to outlines and straight line recognition. They could spot camouflaged positions, buildings and machines because the line stuck out to them.

Percival Lowell, of astronomical fame, saw tons of lines on Mars, inferring canals and manufactured features. He was colorblind and naturally connected the dots by his reckoning. Of course those were not there but he assumed, naturally, straight lines equate to non natural objects. I have observed Mars for 15 years and it was always an indistinct pastel of soft edges but once (emphasize once in 15 years) did see what surely appeared to be lines and I am not colorblind!

My mineralogy partner in school was color blind (surely a handicap) but he was great at making up for in other ways.
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Ru Smith




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PostPosted: Aug 11, 2013 19:29    Post subject: Re: How quartz crystals are formed.  

Really fascinating video, Pierre. Lots of c faces on show! Thank you for sharing it.
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Pierre Joubert




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PostPosted: Aug 12, 2013 02:13    Post subject: Re: How quartz crystals are formed.  

Thanks Ru. Have you any sources to add?
Hi Mark. Thank you for the very interesting story about colourblind people.

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Pierre Joubert




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PostPosted: Sep 16, 2016 02:19    Post subject: Re: How quartz crystals are formed.  

I would like to ad a link to Matt's contribution: 'piezoelectric xtal production for radio use during WW1'

https://www.mineral-forum.com/message-board/viewtopic.php?p=53326#53326

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PostPosted: Sep 16, 2016 02:53    Post subject: Re: How quartz crystals are formed.  

Mark is right about color blind people - we see a rather different version of the world. People have often said that I am very lucky when collecting minerals, but it is not, in my opinion, luck. I just look for different things. You folks look for color while I look for form and other features. The joke with one group of friends used to be 'you are best to follow James and then collect what he leaves behind as he did not see the color'. My best ever find (see https://www.mineral-forum.com/message-board/viewtopic.php?p=35551#35551) was down to that same thing - I could see things other people could not so knew where to look for good specimens (as weird as that sounds).

I have done that exact exercise on an aerial photo and could see far more items than a non-color blind person

Hence my collection is more dominated by form than color.
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Pierre Joubert




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PostPosted: Sep 16, 2016 09:42    Post subject: Re: How quartz crystals are formed.  

James wrote:
Mark is right about color blind people - we see a rather different version of the world. People have often said that I am very lucky when collecting minerals, but it is not, in my opinion, luck. I just look for different things. You folks look for color while I look for form and other features. The joke with one group of friends used to be 'you are best to follow James and then collect what he leaves behind as he did not see the color'. My best ever find (see https://www.mineral-forum.com/message-board/viewtopic.php?p=35551#35551) was down to that same thing - I could see things other people could not so knew where to look for good specimens (as weird as that sounds).

I have done that exact exercise on an aerial photo and could see far more items than a non-color blind person

Hence my collection is more dominated by form than color.


Hi James. Thank you for sharing this with us. When looking for quartz, colour helps very little as they are dirty. I look for shape. I wonder what happened to Mark. Whe have not heard from him for a while.

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