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[Fiebre Verde]

Group of 10+ grass green crystals.
Host rock is a bedded limestone.

[Fiebre Verde]

Beryl crystal partly encapsulated in a calcite shell.
Host rock is black shale.

[Fiebre Verde]

Small beryl crystal has grown on top of the large one.

[Fiebre Verde]

Beryl crystal has a complex pyramidal termination.

[Tobi]

Just too good to be true! Especially the one with the "baby" crystal attached to its top - what a beauty!

[Fiebre Verde]

[Fiebre Verde]

Two intergrown crystals from Chivor.
Very likely from the historic mine of Palo Arañado.

[Michael Shaw]

[Fiebre Verde]

[Fiebre Verde]

Colorless quartz cluster.
Terminations are heavily included with a vivid yellowish-orange material.
Crystals are double-terminated.
This material is from the early 2000s, from an unknown Colombian locality, either in the state of Santander or in Boyacá.
The dealer I got this specimen from believes that the yellowish-orange fibrous inclusions is Humboldtine.

In a recent post, John Rakovan mentioned that these inclusions were being analyzed by his team of the Miami University.
Eagerly waiting for an update on the nature of these inclusions :-)

[Bergur_E_Sigurdarson]

I have seen similar quartz in Colombia... usually told it's from Santander... whether correct or not.
But the ones I have seen aren't usually vivid yellow... the texture of the "fibers" or tubes is the same... but colour ranges from almost white to oxidized brown (similar to the dirt in btw many examples I have seen and bought a few) .... I had always assumed they were just "micro-tubes" getting filled with rust/dirt.

[Philippe Durand]

[Fiebre Verde]

[Fiebre Verde]

The Matecaña mine made the headlines 20 years ago after a pocket full of gastropods was discovered.
These were not ordinary fossils - their shells had been “pseudomorphosed” to emerald following the classic process of “mineralization by dissolution/substitution”
Never had a chance to have an emerald gastropod in my collection but I was lucky to get my first Matecaña specimen only a few days ago.
This druse of deep green crystals arranged in an “en echelon” form looks like a vein crossing the black shale.
But the unique feature of this vein is that outside the emerald, no other mineralization is seen. Contrast of the deep green color with the black shale is spectacular, much better in person.
I was told by a miner who works in the Gachalá area that the black shale found in Matecaña is extremely hard – probably due to the high concentration of silica.

[Fiebre Verde]

Hollow emerald, only found in the Chivor district.
It is admitted that crystals with a central hollow result from rapid growth.