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[Fiebre Verde]

Another "damaged" crystal from the La Pita mining district.
Emerald has a pronounced bluish tinge.
Matrix is pure white calcite.

[Fiebre Verde]

Grey shale host rock is coated with an aggregate of semi-transparent calcite crystals which gives this specimen a velvety shine.
The emeralds have a strong bluish cast and are shaped like long pencil leads.
The main crystal is heavily striated. I have never seen this feature in the Western Belt crystals.
A few dark grey dolomite rhombs can be seen underneath the calcite.
There are thin veins of pyrite running through the grey shale.

Not the finest specimen from Chivor but certainly unusual material from this district.

[Fiebre Verde]

For those who are tired with Colombia, here is a Panjsher specimen.
Matrix is oxidized quartz.

The thicker/smaller emerald has a stunning color.
The longer one is slightly oxidized.

[Fiebre Verde]

This is the Colombian counterpart of the previous specimen (Panjsher #2).
Matrix is pure quartz, partially oxidized.
Note the multiple terminations of the main crystal.
In Peñas Blancas, the emeralds are often saturated and are never far from clear quartz.

[Fiebre Verde]

Fine specimen from Coscuez.
Matrix is dark grey calcite.

[Fiebre Verde]

A crumbly matrix is usually a good indication of a Chivor specimen.
But this piece exceeds the "standard" rusty condition one can expect from a Chivor matrix.
Crystal is unusually long.

This type of material is easy to fake - I have good reasons to believe this one is natural.

[Fiebre Verde]

Colombian green beryl at its best.

Colombian beryls are known for their multiphase inclusions.
The French refer to the large number of inclusions in the stone as "jardin," (French word for garden), because they can resemble plant foliage.
In this crystal, the "jardin" is a combination of inclusions and partially healed cracks and fractures.
These healed cracks are multidirectional and are the main cause of the spectacular sparkling effect that can be observed in this crystal.
Multiphase inclusions and internal cracks and fissures are part of the identity of the Colombian emeralds.

Host rock is grey shale (not featured in the images).

[Fiebre Verde]

A severely corroded beryl crystal.
Main face of the crystal has complex dissolution patterns on the surface.
Interesting to see that one of the edges parallel to the c-axis has been preserved from dissolution.
Despite the presence of small tapered depressions, the flat basal pinacoid termination modified by secondary edge and corner faces is intact.

[Josele]

Last two are superb! and the fool's gold gives a nice contrast.

Not easy see emerald sets like this. Thanks again for sharing these green treasures.

[Fiebre Verde]

Thanks Josele.
Chivor fool's gold can be quite spectacular with sometimes large shiny crystallized nodules.
Attached image is a famous Chivor specimen from the Houston Museum of Natural Science - perhaps the most iconic emerald-pyrite association specimen known.

On the HMNS label, it says:
"The crystallization of the pyrite is very important to the intense color of Colombian emerald, which is generally by far superior to that of any other deposit in the world. It prevented the iron, which would have dulled the color, from being incorporated into the emerald crystal."

Having said that, not all the emerald crystals have an intense color in the presence of unweathered pyrite, but yes, there is definitely a correlation.

Gérard

PS: I decided to post this image in my collection thread even though this piece will probably never find a home in Paris.
It's meant to illustrate the discussion on the Chivor emerald-pyrite association which is I think quite unique and remarkable.
I will try to elaborate on this in my future posts.

[Fiebre Verde]

Nice specimen from Polveros, partly dusted with brownish material (goethite?).

[Fiebre Verde]

Single beryl crystal on a rusty black matrix.

[Fiebre Verde]

Single crystal specimen from Chivor on a rusty, partly oxidized matrix.
Note the 2 major fracture zones orthogonal to the c-axis which affect dramatically the overall aspect of the beryl crystal.

[Fiebre Verde]

Triangle-shaped sparkling specimen from Muzo.
Emerald has a pronounced grayish tone which is not uncommon in Muzo.
Note the presence of elongated depressions on the pinacoid face which is a characteristic feature of the Colombian emeralds.
Black shake host rock is coated by a layer of calcite aggregate.

[Fiebre Verde]

A fine specimen from Cunas with a typical slightly yellowish grass-green color.
Beryl crystals are rather small and are partly damaged.
The creamy dolomite/white calcite matrix is barely noticeable.
But what makes this specimen special is the pristine glassiness of the beryl crystals.
Unfortunately my images do not render this feature very effectively so bear with me if you find some pictures redundant.

[Fiebre Verde]

About a dozen beryl crystals standing on a white calcite crystal aggregate.
One of the crystals has broken into two parts. The two fracture planes on both ends fit perfectly, so there is no doubt this was originally one single and unique crystal.
The color saturation is different from crystal to crystal.

Host rock is black shale (not visible in the images).

[Fiebre Verde]

Emerald on calcite.

[Fiebre Verde]

A classic sample from Coscuez.
Note the complex crystallization patterns on the C-face.
Host rock is black shale.

[Fiebre Verde]

Black calcite and black shale give a nice contrast to the emerald crystal.

[Fiebre Verde]

A doubly-terminated crystal from Polveros.