FMF - Friends of Minerals Forum, discussion and message board

[Ru Smith]

Thanks nurbo,

It varies. I only found one crystal showing the edge modifications on the Ullcoats specimen, whereas most of the Hollywell crystals on that specimen show them - and none of my other Hollywell specimens show any edge or corner modifications at all.

[nurbo]

I discovered 2 more yesterday, one on a sample from Birkett Common in Cumbria and one on a sample i got at Bakewell for £1 labelled "Cowshill" which is a village in Weardale, i'll see if I can get that locality sorted out and get some photo's up in the next couple of days.

[Ru Smith]

Looking forward to the photos, nurbo!

[nurbo]

"A couple of days" hmmm! well 14 :-)

Here is the Birkett Common piece, the Cowshill piece and a Florence Mine piece I've photographed with these modifications. though Im not sure about the Birkett Common one, the curvature at the edges makes me wonder though. The Florence piece is a bit hard to make out, its where the light reflected off the edge I was trying to capture, slightly to the left of centre just above the middle..

[Ru Smith]

Great stuff, nurbo. Good to see these.

[Philip Mostmans]

Very interesting discussion.
As I am cataloging my Fluorite collection I usually can't go any further than describing "modified or bevelled edges".

I wan't to learn how to identify them and correctly name them. What is a good way to start? What books can you recommend for the beginner?

[Ru Smith]

Greetings Philip,

I’d look at the images provided by Roger Warin and Pete Richards on the first page of this thread for the corner modifications: hexoctahedron, trapezohedron and trisoctahedron. Nurbo and I show examples with both trapezohedron and hexoctahedron present. For the edge modifications (dodecahedron with single bevel and tetrahexahedron with double bevel), take a look at the images provided by John Medici.

Do you have some photos to share?

[Ru Smith]

Another nice hexoctahedral corner from Burtree Slitts.

[Ru Smith]

An Emilio Mine, Asturias example.

[Ru Smith]

Another couple of pictures to add.

[Ru Smith]

and I came across this unusual purple hexoctahedral fluorite from Brazil.

[Ru Smith]

Apart from being an extremely unusual penetration twin, I think this image belongs in this thread as it shows well developed trapezoidal icositetrahedron, dodecahedron and cube faces.

[Jordi Fabre]

Considering its quality and interest I renamed, numbered, and moved this topic to the Featured Columns of FMF section.

For more info about how the Featured Columns of FMF section works, please use this link

Ru Smith the author of the first post in this thread and therefore creator of it is already mentioned in the THANK-YOUs in the correspondent reference thread

Jordi

[Ru Smith]

Many thanks, Jordi.

I've found the expert knowledge and wealth of examples shared by the members of this forum hugely rewarding. For me, the progression from knowing almost nothing about a topic at the beginning of one of these threads to quite a lot more towards the end is very satisfying.

[Ru Smith]

These fluorites from Fothergill Sike, Birkett Common, Kirkby Stephen, Cumbria show both tetrahexahedral edge modifications and hexoctahedral corner modifications (ex Ralph Sutcliffe).