We use cookies to show content based on your preferences. If you continue to browse you accept their use and installation. More information. >

FMF - Friends of Minerals Forum, discussion and message board
The place to share your mineralogical experiences

FMF English Forum is moderated by John S. White and Peter Megaw
 

Spanish message board






Newest topics and users posts
15 Jul-16:18:11 Re: sainte marie-aux-mines show 2018 (Roger Warin)
15 Jul-14:55:06 Sainte marie-aux-mines show 2018 / waiting for ste. Marie 2019! (Jordi Fabre)
15 Jul-09:03:39 Re: collection of michael shaw (Crosstimber)
14 Jul-17:32:24 The mizunaka collection - rhodochrosite (Am Mizunaka)
14 Jul-15:20:15 Re: green slime (Justin Hickok)
14 Jul-13:51:53 Re: green slime (Vic Rzonca)
14 Jul-12:02:23 Re: franjungle collection (Franjungle)
13 Jul-23:03:28 Re: green slime (Justin Hickok)
13 Jul-22:17:05 Re: green slime (Justin Hickok)
13 Jul-22:06:08 Re: green slime (Joseph D'oliveira)
13 Jul-21:52:07 Re: green slime (Justin Hickok)
13 Jul-21:27:39 Re: green slime (Matt_zukowski)
13 Jul-21:18:46 Re: apatite? (Amberh)
13 Jul-20:28:55 Re: green slime (Kushmeja)
13 Jul-19:50:29 Green slime (Justin Hickok)
13 Jul-18:08:11 Re: apatite? (Tom Tucker)
13 Jul-17:23:46 Re: collection of fiebre verde (Fiebre Verde)
13 Jul-09:07:59 Re: collection of fiebre verde (Pierre Joubert)
13 Jul-08:10:13 Re: collection of fiebre verde - coscuez (#694) (Fiebre Verde)
13 Jul-04:46:48 Re: collection of heimo hellwig (Heimo Hellwig)
12 Jul-22:17:18 Re: green petrified wood wa state? (Jeff)
12 Jul-19:19:51 Re: green petrified wood wa state? (Bob Morgan)
12 Jul-15:45:58 Re: green petrified wood wa state? (Jenrey1919)
12 Jul-15:21:32 Re: green petrified wood wa state? (Kushmeja)
12 Jul-15:18:47 Re: sainte marie-aux-mines show 2018 (Roger Warin)

For lists of newest topics and postings click here


RSS RSS

View unanswered posts

Why and how to register

Index Index
 FAQFAQ RegisterRegister  Log inLog in
 {Forgotten your password?}Forgotten your password?  

Like
44006


The time now is Jul 15, 2018 21:33

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
Stalactites?
  Goto page Previous  1, 2
  Index -> The Ten Thousand Club
Like
10


View previous topic :: View next topic  
Author Message

lluis




Joined: 17 Nov 2006
Posts: 587

View user's profile

Send private message

PostPosted: Jul 09, 2018 03:19    Post subject: Re: Stalactites?  

"The fact that both styles of rhomb-stacking occur on the same specimen suggests that something changed and caused the spiraling to begin after the straight growth stage....chemical or simply physical???
Peter Megaw
PostPosted: Jul 08, 2018 16:00 Post subject: Re: Stalactites?"

Hard to say..... As a physics teacher said one time to a friend of mine that studied Physics, "Chemistry is only a cancer of Physics. Pity is that tumor is bigger than body!"
At those levels, just a question of chemical-physics, I guess...

With best wishes

Lluís
Back to top
Reply to topic Reply with quote
Like
   

Roger Warin




Joined: 23 Jan 2013
Posts: 855


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 09, 2018 09:02    Post subject: Re: Stalactites?  

Growth of a crystal.

The growth mechanisms of the crystal seed are varied. They are correlated with the growth rates of the faces, that is with the kinetics of crystallization: either the growth is slow and two-dimensional and one obtains plane faces, or it appears screw dislocations, or even spirals according to the speed of growth.
The geometry of the atomic site varies according to surface irregularities. Some external bonds remain vacant, occupied on the surface by ligands of the hydrothermal solution which must be displaced by the deposition of a new atom of the molecule which crystallizes.
The presence of natural catalytic effects is possible by the presence of impurities in the hydrothermal phase.
Thus the crystal takes its habit.
In the case of spiral crystals, the elongation is maximal.
There is another type of spiral growth for chiral species, such as quartz. In this case, it is subparallel growths that introduce the spiral deformation as for twisted quartz (or Gwindels) with a double possibility.
At least that's what I think, and you?
Back to top
Reply to topic Reply with quote
Like
   

lluis




Joined: 17 Nov 2006
Posts: 587

View user's profile

Send private message

PostPosted: Jul 09, 2018 10:06    Post subject: Re: Stalactites?  

Hi, Roger

I think I said same as you: it is chemical-physics.... (for a physician, physical-chemistry... No need to explain that chemist and physicists do not go alongs very well..... :-))

With best wishes

Lluís
Back to top
Reply to topic Reply with quote
Like
   

Bob Harman




Joined: 06 Nov 2015
Posts: 344
Location: Indiana


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 09, 2018 10:11    Post subject: Re: Stalactites?  

Somewhat similar to Tracy's 2008 pictured quartz examples are these 2 examples from Indiana. The first is a "stalactite" type grouping of tiny individual terminated and doubly terminated quartz crystals. The second example is more of a "free form" growth of similar tiny terminated and doubly terminated quartz crystals. I have others as well. How these form has always intrigued me.


fullsizeoutput_29e0.jpeg
 Mineral: Quartz
 Locality:
Indiana, USA
 Dimensions: The quartz crystals are about 1mm each. Some crystals are doubly terminated. The free form area is 2.8 cm
 Description:
Acquired in 2011.
 Viewed:  241 Time(s)

fullsizeoutput_29e0.jpeg



t_fullsizeoutput_29de_800.jpeg
 Mineral: Quartz
 Locality:
Indiana, USA
 Dimensions: The quartz crystals are 1mm. Some crystals are doubly terminated. The whole "stalactite" is 2.5 cm
 Description:
Self collected about 2008
 Viewed:  232 Time(s)

t_fullsizeoutput_29de_800.jpeg


Back to top
Reply to topic Reply with quote
Like
1
   

lluis




Joined: 17 Nov 2006
Posts: 587

View user's profile

Send private message

PostPosted: Jul 09, 2018 10:20    Post subject: Re: Stalactites?  

Hi, Bob

Here, to me, it is less stunning than the stalactite brought to us by Peter Megaw...
In this case, it is just a quick crystallization, growing in all places it can. Some would be in a shape, some in another... maybe just a difference in the flow of components....
Again, chemical-physics. But to my eyes, far less spectacular...

With best wishes

Lluís
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> The Ten Thousand Club   All times are GMT - 5 Hours
Page 2 of 2
  Goto page Previous  1, 2  

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


All pictures, text, design © Forum FMF 2006-2018


Powered by FMF