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[Sante Celiberti]

Thank you, Bob, for your prompt and thorough reply.

Warm greetings.
Sante

[Sante Celiberti]

Hello, LDMarks.

Returning to the original theme of your first post, perhaps this can be of some interest to you.

The Niccioleta pyrite mine is very rich in sulfur and has produced very interesting samples of this element, often associated with calcite and quartz, but above all with gypsum and pyrite.
I do not rule out that there may be other pyrite mines that also produce native sulfur, but I am not aware of them.
Although Niccioleta has produced pyrite samples with pentagonal-dodecahedral habit and combinations of cube and pyritohedron, it is renowned for its cubic crystals that sometimes exceed 20 cm.

Here are the reflections and doubts of a simple amateur.

I have found that here the sulfur is always associated with cubic pyrite.
The selective deposition of sulfur on cubic crystals, which at first sight seems to contradict the thesis of the influence of sulfur on the crystal morphology, could actually be a confirmation of this thesis if we assume that the cubic crystals of pyrite, less saturated with sulfur compared to the pyritohedra, attract it more easily.

There remains a basic question.
It is true that the native sulfur that accompanies these samples is of a new generation and that it has nothing to do with the morphology of the underlying pyrite.
But, if a greater availability of sulfur tends to favor a pyritohedral habit, why did the Niccioleta mine produce a much greater quantity of cubic pyrite?
The possibility that the geological environment has changed radically from the first generation of pyrite to the second generation of sulfur, although plausible, seems to me a little exhaustive explanation.
What do you think?

Warm greetings from Gavorrano.
Sante