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Improving Mindat.orgfluorite crystal form: hexoctahedron instead of tetrahexahedron

9th Apr 2024 02:08 UTCHerwig Pelckmans

Fluorite

Highway 105, Old Chelsea, Chelsea, Les Collines-de-l'Outaouais RCM, Outaouais, Québec, Canada

See https://www.mindat.org/photo-1364507.html

and all the child photos/video

The description states the major crystal is a tetrahexahedron, but it is not.

Some photos and the video clearly show it to be a hexoctahedron.

Please adapt the captions accordingly.

The photo above shows the edges between the octahedral "faces" are not straight lines (as they should be for a tetrahexahedron).

9th Apr 2024 07:37 UTCJosé Zendrera 🌟 Manager

I think description is correct and the form is indeed a tetrahexahedron.
An hexoctahedron should have 48 faces and this one have only 24, plus to the octahedral modifications in corners.

14th Apr 2024 05:51 UTCHerwig Pelckmans

José,

I'm sorry, but we can not see all the faces, nor count them all, so that is not an argument.

If the crystal was a tetrahexahedron, then there should not be any difference in the way light was reflected by the "face" on the upper left of the specimen.

But there is a slight difference in reflection, and that is because there are 2 faces, at a slightly different orientation. Consequently, the form is a hexoctahedron.

Thank you, Johan, for adding your observations.

9th Apr 2024 08:31 UTCJohan Kjellman Expert

Even though the tetrahexaedral faces are continuous, there is a slight beveling on them, suggesting that there is "something hexoctaedral" going on. This can be seen clearly in the 9th picture, particularily on the left where the bevelling is modified by what seems to be a "lenticular" (not straight) dodecahedral face.

14th Apr 2024 07:51 UTCErik Vercammen Expert

Don't forget that in natural crystals, not all faces are equally developed.