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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 ...

Author	Message
Topic: Pyrite with bubble-like growths
Reef Replies: 21 Views: 23596	Forum: Minerals and Mineralogy Posted: Jan 08, 2021 16:25 Subject: Re: Pyrite with bubble-like growths
Reef Replies: 21 Views: 23596	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: 58501	Forum: Minerals and Mineralogy Posted: Feb 06, 2020 11:36 Subject: Re: Weird face in quartz
Reef Replies: 32 Views: 58501	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: 12081	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: 12081	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: 20642	Forum: Minerals and Mineralogy Posted: Nov 30, 2017 05:23 Subject: Re: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 20642	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: 20642	Forum: Minerals and Mineralogy Posted: Nov 27, 2017 12:59 Subject: Re: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 20642	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: 20642	Forum: Minerals and Mineralogy Posted: Nov 27, 2017 05:45 Subject: "Frosted patterns" on the faces of Quartz
Reef Replies: 10 Views: 20642	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: 72176	Forum: Minerals and Mineralogy Posted: Nov 21, 2017 11:20 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	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: 58501	Forum: Minerals and Mineralogy Posted: Nov 15, 2017 11:10 Subject: Re: Weird face in quartz
Reef Replies: 32 Views: 58501	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: 72176	Forum: Minerals and Mineralogy Posted: Nov 09, 2017 11:25 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	... 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: 72176	Forum: Minerals and Mineralogy Posted: Nov 08, 2017 11:38 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	Josele, good luck with your search ! Reichenstein - Griesernthal law twin
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	Forum: Minerals and Mineralogy Posted: Nov 04, 2017 12:50 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	Friedel Law Twin Angle 90°
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	Forum: Minerals and Mineralogy Posted: Nov 04, 2017 12:01 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	Zwickau law twin Angle 42°17'
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	Forum: Minerals and Mineralogy Posted: Nov 04, 2017 11:56 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	Breithaupt law twin Angle 48°54'
Topic: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	Forum: Minerals and Mineralogy Posted: Nov 04, 2017 11:02 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	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: 72176	Forum: Minerals and Mineralogy Posted: Nov 03, 2017 05:26 Subject: Re: Rarest quartz twins with inclined axes C
Reef Replies: 42 Views: 72176	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 ...