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Hello everybody!
This is probably due to anti skeletal growth. Crystals of a cubic system during anti skeletal growth under ideal conditions grow in the form of a ball.
The area of each subsequent l ...

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).
I apologize ...

In the Sella law twin, the indicated faces of the rhombohedrons must be parallel

A request, who has similar samples with a "dendritic" pattern, publish a photo.
A few more photos.

I do not know how this is formed, but interesting and beautiful. In my opinion there is no etching here. Whims of skeletal growth. Host rocks: calcareous sandstone, marl, calcite, dolomite. The veins ...

I would call this dendritic growth. But it is believed that quartz can not have it.
The sizes of the samples are mainly up to ~ 15 mm.
Locality: Alatau, Bashkortostan Republic, Southern Urals, Ura ...

Another law of twinning quartz under the working title "Ural". Theoretically, this law has already been predicted. Samples that confirm this law have not been found so far. It is an analogue ...

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.

... So first, my question is how were these angles measured?
If there is a parallelism of faces and edges, as in diagrams, then there is no doubt. It will be a twin. It remains only to make sure of ...

Josele, good luck with your search !

Reichenstein - Griesernthal law twin

Friedel Law Twin
Angle 90°

Zwickau law twin
Angle 42°17'

Breithaupt law twin
Angle 48°54'

I agree, pleasant twins.
The costs of machine translation. The main thing is for people to understand what the conversation is about.

Continue..
Goldschmidt law twin
Angle 47°43'

Can anyone confirm or disprove this opinion (previous message)? If such splices (a prism to a prism) do not contradict the laws of twinning, then the circle of search for twins will expand. And we can ...

Hi Jordi. Thank you. Overlooked.

Another variant of the arrangement is in the twins of the Japanese type.
There was a splicing of prisms. A small crystal is located on the prism of a large crysta ...

The concept of two equal individuals in twins is wrong.
In the laws of twinning, there is no condition for the relative dimensions of subindivids.
Here are some examples.
Japan Law Twin

Pete, thanks for the corrections. About the schematic drawings, a little prehistory. Two years ago I became interested in quartz twins. According to the book K. Frondel at first absolutely did not und ...

One of the most favorite types of twinning
Disentis law twin

Pete, thanks for the clarification.I did only visualization of these twinning laws. So far, nothing new has been proposed. In the literature there are only descriptions or mentions of these laws, and ...

Author	Message
Topic: Pyrite with bubble-like growths
Reef Replies: 21 Views: 15411	Forum: Minerals and Mineralogy Posted: Jan 08, 2021 16:25 Subject: Re: Pyrite with bubble-like growths
Reef Replies: 21 Views: 15411	Hello everybody! This is probably due to anti skeletal growth. Crystals of a cubic system during anti skeletal growth under ideal conditions grow in the form of a ball. The area of each subsequent l ...
Topic: Weird face in quartz
Reef Replies: 32 Views: 48570	Forum: Minerals and Mineralogy Posted: Feb 06, 2020 11:36 Subject: Re: Weird face in quartz
Reef Replies: 32 Views: 48570	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). I apologize ...
Topic: V-Twin Found in Washington
Reef Replies: 7 Views: 10472	Forum: What is it? - Where is it from? Posted: Feb 05, 2020 04:49 Subject: Re: V-Twin Found in Washington
Reef Replies: 7 Views: 10472	In the Sella law twin, the indicated faces of the rhombohedrons must be parallel
Topic: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 15935	Forum: Minerals and Mineralogy Posted: Nov 30, 2017 05:23 Subject: Re: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 15935	A request, who has similar samples with a "dendritic" pattern, publish a photo. A few more photos.
Topic: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 15935	Forum: Minerals and Mineralogy Posted: Nov 27, 2017 12:59 Subject: Re: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 15935	I do not know how this is formed, but interesting and beautiful. In my opinion there is no etching here. Whims of skeletal growth. Host rocks: calcareous sandstone, marl, calcite, dolomite. The veins ...
Topic: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 15935	Forum: Minerals and Mineralogy Posted: Nov 27, 2017 05:45 Subject: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 15935	I would call this dendritic growth. But it is believed that quartz can not have it. The sizes of the samples are mainly up to ~ 15 mm. Locality: Alatau, Bashkortostan Republic, Southern Urals, Ura ...
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Nov 21, 2017 11:20 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Another law of twinning quartz under the working title "Ural". Theoretically, this law has already been predicted. Samples that confirm this law have not been found so far. It is an analogue ...
Topic: Weird face in quartz
Reef Replies: 32 Views: 48570	Forum: Minerals and Mineralogy Posted: Nov 15, 2017 11:10 Subject: Re: Weird face in quartz
Reef Replies: 32 Views: 48570	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.
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Nov 09, 2017 11:25 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	... So first, my question is how were these angles measured? If there is a parallelism of faces and edges, as in diagrams, then there is no doubt. It will be a twin. It remains only to make sure of ...
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Nov 08, 2017 11:38 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Josele, good luck with your search ! Reichenstein - Griesernthal law twin
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Nov 04, 2017 12:50 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Friedel Law Twin Angle 90°
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Nov 04, 2017 12:01 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Zwickau law twin Angle 42°17'
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Nov 04, 2017 11:56 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Breithaupt law twin Angle 48°54'
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Nov 04, 2017 11:02 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	I agree, pleasant twins. The costs of machine translation. The main thing is for people to understand what the conversation is about. Continue.. Goldschmidt law twin Angle 47°43'
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Nov 03, 2017 05:26 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Can anyone confirm or disprove this opinion (previous message)? If such splices (a prism to a prism) do not contradict the laws of twinning, then the circle of search for twins will expand. And we can ...
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Oct 31, 2017 09:29 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Hi Jordi. Thank you. Overlooked. Another variant of the arrangement is in the twins of the Japanese type. There was a splicing of prisms. A small crystal is located on the prism of a large crysta ...
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Oct 30, 2017 15:51 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	The concept of two equal individuals in twins is wrong. In the laws of twinning, there is no condition for the relative dimensions of subindivids. Here are some examples. Japan Law Twin
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Oct 27, 2017 07:48 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Pete, thanks for the corrections. About the schematic drawings, a little prehistory. Two years ago I became interested in quartz twins. According to the book K. Frondel at first absolutely did not und ...
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Oct 26, 2017 10:37 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	One of the most favorite types of twinning Disentis law twin
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Forum: Minerals and Mineralogy Posted: Oct 26, 2017 08:10 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 54172	Pete, thanks for the clarification.I did only visualization of these twinning laws. So far, nothing new has been proposed. In the literature there are only descriptions or mentions of these laws, and ...