FMF - Friends of Minerals Forum, discussion and message board

I think I'm starting to "get" the different classes of calcite twin.

Here's an old page of drawings from Dana and a selection of four twins to represent the four classes (if I've underst ...

Love the orange tinge of the hemimorphite. It's a wonderfully colourful group of Mexican minerals that you show.

While I have the camera out - a pretty spinel twin of diamond.

Thanks Roger,

Here's a similar one from Dalnegorsk and also another view of the more common habit in the Meikle example, with twin rotated to show composition plane horizontal.

These Rodderup/Rotherhope Fell Mine fluorites are very beautiful. I also like the calcites from there.

Thanks Roger. As usual though it's still not as ideal as in the drawing. Here I've rotated a photo to compare with the old Dana drawing.

I particularly like the Meikle example.

Something tiny from Cumbria.

Fine examples, Ian.

Here's an interesting cyclic arrangement of spinel twins from Myanmar.

Homoepitaxy it is then!

Two of several beautiful twins to 65 mm on 26 cm matrix.

My favourite: the cacoxenite from La Paloma.

This is a fun little example of epitaxy - galena octahedra on corners and sides of an earlier cube.

Fine old tetrahedrite.

Author	Message
Topic: Calcite Forms - (4)
Ru Smith Replies: 163 Views: 385515	Forum: Featured Columns of FMF Posted: Oct 05, 2013 13:19 Subject: Re: A couple of American Calcite Twins
Ru Smith Replies: 163 Views: 385515	I think I'm starting to "get" the different classes of calcite twin. Here's an old page of drawings from Dana and a selection of four twins to represent the four classes (if I've underst ...
Topic: Don Lum Collection
Ru Smith Replies: 2247 Views: 2639497	Forum: Collection photos and Collector's page Posted: Oct 05, 2013 11:04 Subject: Re: Don Lum Collection
Ru Smith Replies: 2247 Views: 2639497	Love the orange tinge of the hemimorphite. It's a wonderfully colourful group of Mexican minerals that you show.
Topic: Spinel twins
Ru Smith Replies: 54 Views: 141521	Forum: Minerals and Mineralogy Posted: Oct 04, 2013 18:32 Subject: Re: Spinel twins
Ru Smith Replies: 54 Views: 141521	While I have the camera out - a pretty spinel twin of diamond.
Topic: Calcite Forms - (4)
Ru Smith Replies: 163 Views: 385515	Forum: Featured Columns of FMF Posted: Oct 04, 2013 18:28 Subject: Re: A couple of American Calcite Twins
Ru Smith Replies: 163 Views: 385515	Thanks Roger, Here's a similar one from Dalnegorsk and also another view of the more common habit in the Meikle example, with twin rotated to show composition plane horizontal.
Topic: A mineralogical trip through the regions of the UK - England / Cumbria
Ru Smith Replies: 141 Views: 263876	Forum: A mineralogical trip through the regions of the UK Posted: Oct 04, 2013 18:00 Subject: Re: A mineralogical trip through the regions of the UK - England / Cumbria
Ru Smith Replies: 141 Views: 263876	These Rodderup/Rotherhope Fell Mine fluorites are very beautiful. I also like the calcites from there.
Topic: Spinel twins
Ru Smith Replies: 54 Views: 141521	Forum: Minerals and Mineralogy Posted: Oct 03, 2013 22:31 Subject: Re: Spinel twins
Ru Smith Replies: 54 Views: 141521	Thanks Roger. As usual though it's still not as ideal as in the drawing. Here I've rotated a photo to compare with the old Dana drawing.
Topic: Calcite Forms - (4)
Ru Smith Replies: 163 Views: 385515	Forum: Featured Columns of FMF Posted: Oct 03, 2013 21:33 Subject: A couple of American Calcite Twins
Ru Smith Replies: 163 Views: 385515	I particularly like the Meikle example.
Topic: A mineralogical trip through the regions of the UK - England / Cumbria
Ru Smith Replies: 141 Views: 263876	Forum: A mineralogical trip through the regions of the UK Posted: Oct 03, 2013 21:26 Subject: Re: A mineralogical trip through the regions of the UK - England / Cumbria
Ru Smith Replies: 141 Views: 263876	Something tiny from Cumbria.
Topic: A mineralogical trip through the regions of the UK - England / Cornwall
Ru Smith Replies: 76 Views: 164610	Forum: A mineralogical trip through the regions of the UK Posted: Oct 03, 2013 21:23 Subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall
Ru Smith Replies: 76 Views: 164610	Fine examples, Ian.
Topic: Spinel twins
Ru Smith Replies: 54 Views: 141521	Forum: Minerals and Mineralogy Posted: Oct 01, 2013 21:35 Subject: Re: Spinel twins
Ru Smith Replies: 54 Views: 141521	Here's an interesting cyclic arrangement of spinel twins from Myanmar.
Topic: Galena "homoepitaxy"
Ru Smith Replies: 2 Views: 8024	Forum: Minerals and Mineralogy Posted: Sep 29, 2013 23:05 Subject: Re: Galena "homoepitaxy"
Ru Smith Replies: 2 Views: 8024	Homoepitaxy it is then!
Topic: Calcite Forms - (4)
Ru Smith Replies: 163 Views: 385515	Forum: Featured Columns of FMF Posted: Sep 29, 2013 22:57 Subject: Re: Calcite Forms - (4)
Ru Smith Replies: 163 Views: 385515	Two of several beautiful twins to 65 mm on 26 cm matrix.
Topic: My modest collection of minerals / micro photos ...
Ru Smith Replies: 59 Views: 132842	Forum: Micros & Macros - Images of Minerals Posted: Sep 29, 2013 22:48 Subject: Re: My modest collection of minerals / micro photos ...
Ru Smith Replies: 59 Views: 132842	My favourite: the cacoxenite from La Paloma.
Topic: Galena "homoepitaxy"
Ru Smith Replies: 2 Views: 8024	Forum: Minerals and Mineralogy Posted: Sep 28, 2013 18:29 Subject: Galena "homoepitaxy"
Ru Smith Replies: 2 Views: 8024	This is a fun little example of epitaxy - galena octahedra on corners and sides of an earlier cube.
Topic: A mineralogical trip through the regions of the UK - England / Cornwall
Ru Smith Replies: 76 Views: 164610	Forum: A mineralogical trip through the regions of the UK Posted: Sep 28, 2013 18:21 Subject: Re: A mineralogical trip through the regions of the UK - England / Cornwall
Ru Smith Replies: 76 Views: 164610	Fine old tetrahedrite.