FMF - Friends of Minerals Forum, discussion and message board

[Jordi Fabre]

Recently, this piece has been published: https://www.mineral-forum.com/message-board/download.php?id=110019, and as I remain intrigued to find out if these twinned Pyrites are truly from Gachalá or if they are actually from the iron mine El Santuario, in Ubalá, Cundinamarca Department, Colombia.

Does anyone know more about this topic?

[Fiebre Verde]

[James Catmur]

That often happens, that the nearest major town becomes the default locality for many mines in the surrounding area.

[Bergur_E_Sigurdarson]

I agree with Gerard,
all my better sources say that the iron cross twins come from the El Santuario mine or minor diggings near it and thus not Gachala municipality but Ubala.
One close by is La Mercedes, which I've heard once.

My explanation of the "confusion" is slightly different to Gerards.

Gachala and Ubala are quite similar size villages... but mineral digging isn't that close to Gachala either.
But... in the mineral world people know Gachala, (even if they don't know Palomas or Vega de San Juan where the specimens actually come from)... but to explain then something from that area... as the El Santuario and Mercedes are close Palomas and Vega de San Juan... they just mention the closest known mineral area.... being Gachala.

Attached a map of the area

[alfredo]

I think floater pyrite crystals would be unlikely to be associated with iron ore. Floater pyrites are found in shale, limestone, and some types of schist... but in iron ore? So I have doubts about that iron mine being the origin.

[Jordi Fabre]

Thank you all!
I have already created the locality and applied it to the mentioned piece.

[Roger Warin]

Thank you Jordi for these details.
I modified the “Gachala” label of the specimen purchased in 2019, next to your stand.
Obviously this twin is a solitary aggregate. But I think (without being certain) that the geologist can better specify the deposit because this twin crystallizes in the “high temperature” zone of its state diagram.

[John S. White]

These twins are remarkable, in part for their consistent perfection and also for their great abundance. I am not aware of any other occurrence that even begins to match this one. I was fortunate to have found them for sale when they first appeared in Tucson, and they were very cheap. I bought several but I should have bought more because they became more expensive after the dealers realized they could be sold for higher prices. Nevertheless, I feel they are still very affordable, and I hope that anyone who wants a great iron cross pyrite twin will buy one or more while they last.

[Michael Shaw]

As Alfredo points out, floater pyrite crystals are generally found in shales, limestones and schists, and would be unlikely to be associated with ore from an iron mine. So..... I am inclined to think that these iron cross twins likely do not originate from the El Sanctuario mine.

Like John White, I obtained one of these specimens in Tucson when they first came onto the market. I purchased my specimen from Henry Ospina, a Colombian mineral dealer. He indicated that they were collected from the upper horizons of the Matacana Mine, Gachala, Cundinamarca Dept., Colombia.

[alfredo]

The Matacana mine makes more sense, geologically, than an iron mine but, since Colombian sellers are notoriously secretive about the provenance of their wares, and mystification is de rigeur, I think it is premature to assign a locality, and almost certainly not the iron mine.
I can easily imagine someone thinking, "Oh, "iron cross", something to do with iron then, so let's put the name of an iron mine."
I've had similar problems trying to get accurate info out of Colombia for their schungite, the "colombianite" glass, quartz crystals...

[Jordi Fabre]

That's why, in the meantime, we use:

'El Santuario Mine area'