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[Fiebre Verde]

There are sprays of acicular aragonite all over the specimen.
White and colorless calcite set in a brecciated matrix with patches of black shale and grey limestone.

[Fiebre Verde]

In Colombia, the different districts and localities are known to produce emeralds that differ significantly in color, tone, and clarity.
Even if some trends have been observed it’s difficult to apply a rigid locality (or area) classification scheme based on color features alone when presented with an emerald specimen (or even worse, a faceted stone!).
Muzo emeralds are supposedly saturated, slightly yellowish green whereas Chivor emeralds are less saturated and exhibit a slight bluish tinge. But the opposite also occurs.
Color classification is mainly driven by the jewelry industry (with the help and creativity of some labs) which often refers to the beauty of the Colombian faceted emerald using a questionable terminology to describe their color features.

Back to this Chivor specimen… Although the crystals exhibit a slight bluish tinge, they are far more saturated than the average saturation of the Muzo crystals.
San Gregorio is known for producing relatively small but highly saturated crystals.
Lustrous dolomite, pyrite, on a crumbly grey shale.

[Fiebre Verde]

The beryl prism of this Coscuez specimen is partially coated with tiny calcite crystals.
Host rock is a coarse-grained black shale

[Fiebre Verde]

Calceteros mine also known as “Calcetero” or “El Calcetero” is located almost halfway between the historic mining areas of Coscuez and Peñas Blancas.
The emerald deposits of Coscuez and Calceteros are situated in the lower cretaceous Paja rocks units formation whereas the Peñas Blancas deposits are hosted by the (younger) Rosa Blanca formation (also lower cretaceous).
Based on this geological formation criteria alone, it was decided to attach the Calceteros locality to the Coscuez district rather than to Peñas Blancas.

I only have a handful of specimens from Calceteros and they exhibit some common features.
E.g. Oxidized coarse-grained black shale, coarse-grained aggregates of albite, quartz.
Beryl crystals are grouped into aggregates of small (<1cm) light green prisms with either a yellowish or bluish tinge.
Terminations often exhibit pyramidal faces combined with the flat pinacoid face.
The secondary color here is clearly yellow.

It’s impossible to draw conclusions about patterns and characteristics of this not so well-known locality with just a handful of specimens.
These are just basic observations which need to be corroborated by additional evidence which would require many more samples from additional finds!

[Fiebre Verde]

From a relatively recent find (2011) in the Chivor district.
Host rock is black shale.

[Philippe Durand]

striking combination

[Fiebre Verde]

[Jamison Brizendine]

This thread never ceases to amaze me!

I particularly like the specimen from the Calceteros Mine (IMG_5152nb.JPG) and the emerald in the calcite/quartz vein from Chivor (IMG_4149nb.JPG).

I also like the aragonite and calcite specimen from Chivor as well (IMG_4840nb.JPG). What a cool oddity...

[Tobi]

[Fiebre Verde]

[Fiebre Verde]

Another oddity, from Muzo this time.
Parisite was named after J.J. Paris, a former manager of the Muzo mine, who found this rare carbonate mineral in 1835.

Host rock is black shale.

[Fiebre Verde]

Beryl crystal intergrown with lustrous dolomite.
Host rock is black shale.

[Fiebre Verde]

Glowing crystal with a complex asymmetric pyramidal termination perched on an aggregate of snowy white coarse-grained albite.

[Tobi]

[Fiebre Verde]