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
26 Mar-01:40:14 The mizunaka collection - quartz (Am Mizunaka)
25 Mar-18:18:58 Re: cr-rich green tremolite (Bob Harman)
25 Mar-17:44:54 Re: cr-rich green tremolite (Susan Robinson)
25 Mar-16:23:55 Re: cr-rich green tremolite (R Saunders)
25 Mar-13:55:39 Re: cr-rich green tremolite (Susan Robinson)
25 Mar-13:25:58 Re: franjungle collection (Firmo Espinar)
25 Mar-11:26:14 Re: quartz collecting outings in south africa (Pierre Joubert)
25 Mar-10:43:34 Re: quartz collecting outings in south africa (Heimo Hellwig)
25 Mar-10:30:50 Re: quartz collecting outings in south africa (Pierre Joubert)
25 Mar-10:27:41 Re: quartz collecting outings in south africa (Pierre Joubert)
25 Mar-08:53:04 Re: collection of michael shaw (Crosstimber)
25 Mar-08:52:07 Re: cr-rich green tremolite (Jonathan Zvonko)
25 Mar-08:32:13 Re: collection of enrique llorens (Enrique Llorens)
25 Mar-06:56:49 Re: a mineralogical trip through the states of usa - new york (Pierre Joubert)
25 Mar-06:52:34 Re: carlos pareja photo collection (Pierre Joubert)
25 Mar-05:46:56 Re: collection of enrique llorens (Susan Robinson)
25 Mar-05:40:43 Re: cr-rich green tremolite (Susan Robinson)
25 Mar-04:35:24 Cr-rich green tremolite (R Saunders)
25 Mar-02:21:27 Re: collection of enrique llorens (Enrique Llorens)
25 Mar-00:15:28 Re: collection of heimo hellwig (Heimo Hellwig)
24 Mar-16:32:33 Re: collection of enrique llorens (Enrique Llorens)
24 Mar-13:03:41 Re: don lum collection (Don Lum)
24 Mar-06:33:05 Re: carlos pareja photo collection (Carlos Pareja)
23 Mar-17:02:47 Re: don lum collection (Don Lum)
23 Mar-16:38:41 Re: women's private collection sub-forum (J. G. Alcolea)

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
53101


The time now is Mar 26, 2019 03:58

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
Rarest quartz twins with inclined axes C
  Goto page Previous  1, 2, 3
  Index -> Minerals and Mineralogy
Like
29


View previous topic :: View next topic  
Author Message

Recovering - Academic




Joined: 24 Apr 2018
Posts: 316

View user's profile

Send private message

PostPosted: Nov 09, 2018 18:12    Post subject: Re: Rarest quartz twins with inclined axes C  

John S. White wrote:
It may seem a small point but the proper name for the twin is Japan law twin, not Japanese twin. Japanese twins are properly represented in the attached image.


REAL JAPAN LAW TWINS



JAPAN LAW TWINS.jpg
 Description:
 Viewed:  367 Time(s)

JAPAN LAW TWINS.jpg



_________________
“The further a society drifts from the truth, the more it will hate those that speak it.”

― George Orwell
Back to top
Reply to topic Reply with quote
Like
   

Recovering - Academic




Joined: 24 Apr 2018
Posts: 316

View user's profile

Send private message

PostPosted: Nov 09, 2018 18:16    Post subject: Re: Rarest quartz twins with inclined axes C  

Interesting!!
_________________
“The further a society drifts from the truth, the more it will hate those that speak it.”

― George Orwell
Back to top
Reply to topic Reply with quote
Like
   

Recovering - Academic




Joined: 24 Apr 2018
Posts: 316

View user's profile

Send private message

PostPosted: Nov 09, 2018 18:17    Post subject: Re: Rarest quartz twins with inclined axes C  

Bob Morgan wrote:
At the risk of adding confusion to this discussion, I prefer to call what Pete calls auto-epitaxy deposition twins. This is where a smaller crystal develops on an already established larger crystal and does so according to the twin law showing the same characteristic morphology of 'v' twins. This is quite common with Japan Law twinning. It is true of quite a lot of Greiserntal Law twins. In both cases there is more rapid growth in the twin notch, rapid widening of the smaller crystal, and markedly less growth in the supplemental angle on the other side of the smaller crystal. If the larger crystal is clear, the twin composition plane shows and is consistent with the twin law.
These depositions can be oriented in either of two directions 1) with the twin angle toward the termination of the larger crystal or 2) with the twin angle toward the base of the larger crystal. There are several instances where a larger crystal hosts separate twins of both orientations.


Now, this leads me to comment on the supposedly Reichenstein Law. There is no rational twin plane or twin axis for such a law. The photo's showing parallel pyramidal faces are therefore just the supplementary angle to the Greiseerntal Law twin that is oriented toward the larger crystal's base. Note too, that Japam Law twins have two sets of parallel pyramidal faces across the supplementary 96 degree angle, and that's not a separate twin law.


Interesting!!!

_________________
“The further a society drifts from the truth, the more it will hate those that speak it.”

― George Orwell
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> Minerals and Mineralogy   All times are GMT - 5 Hours
Page 3 of 3
  Goto page Previous  1, 2, 3  

 
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 2006-2019


Powered by FMF