FMF - Friends of Minerals Forum, discussion and message board

[Bergur_E_Sigurdarson]

A lot easier to give comments on specimens seen in person than of photos obviously.
I would venture a guess on the lustrous brown crystals to be grey dolomite, just with some iron staining and even micro-inclusions of ferrous types.

I have seen several times in the matrix from Chivor area that under UV glow some crystals in pink... I presume these to be fluorapatite, just that they are either faded or never got their pale pink colour.
It is excellent to see a sample that has nicely formed crystals of color next to the emerald crystals themselves :-)

[Fiebre Verde]

Here is an oddity from Chivor - a dome-like crystal which has been contacted from all sides.
The upper crystal (image 1994) is also showing multiple contact areas.
Host rock is black shale.

[Fiebre Verde]

Glowing translucent (striated) calcite matrix included with carbonaceous material.
Patches of black shale on the back.

[Fiebre Verde]

Not everything is green in Muzo.

[Fiebre Verde]

Catching up on my backlog of photos...
Here is a nice little specimen from Coscuez.

[Fiebre Verde]

The first emerald occurrence in the Gachalá area was incidentally found by a farmer of La Vega de San Juan in the early 1950s.
The farmer hid his discovery for a while but eventually confided in a friend about it.
It wasn't long before the word went round in all the emerald circles in Bogota and in 1953, 100s of adventurers dashed to the new bonanza. The Colombian government had to send in the army to take control and restore order.
Formal mining started in the late 50s.
That's how this new emerald district of the Eastern Belt was born - a pretty classic story.

In Gachalá, emeralds occur in limonite or kaolin deposits in fractures which explains why in matrix specimens are difficult to obtain.

These 3 Gachalá specimens are among the most famous emerald specimens which have been found in Colombia:
'The Gachalá Emerald' found in La Vega de San Juan mine in 1967 – 5cm x 5cm x 5cm, 858 cts – On display at Smithsonian's Natural History Museum in Washington D.C.
'La Emilia' found in Las Cruces mine in 1969 – 7,025 cts – Current whereabouts unknown
'El Monstro' found in Las Cruces mine in 1986 – 16,020 cts, a monster of 3,204 grams!! Possibly the largest emerald crystal ever found – Current whereabouts unknown

Gachalá specimens are not easy to find these days and I am pretty happy to have this less than 3-carat crystal in my collection ;-)
Matrix is oxidized which prevents identifying associated minerals.

[Fiebre Verde]

Still catching up on my photos...

On my last trip to Colombia, I was really lucky to find two specimens "fresh from the mine" (as they sometimes say before Christmas - it helps drawing customer's attention and adds a significant premium to the price which in turn helps cover Christmas expenses).
As there is currently a serious shortage of natural specimens, there is also plenty of "fresh from the lab" artwork available in the market (sold usually at the price of natural specimens).

Here is the first specimen (*not* artwork).
Semi-transparent beryl crystals with a typical Chivor bluish-green color standing on a white laminar albite matrix.

Second specimen is on the way ;-)

[Philippe Durand]

that is a cute thumbnail

[Fiebre Verde]

[Fiebre Verde]

This is the other specimen I was mentioning in my previous post.

Happy New Year to everyone!

[Fiebre Verde]

Chivor specimen from an old collection.
Calcite matrix with patches of black shale.

[Fiebre Verde]

Rare crystal topped by an atypical pointed termination.
'Botella' (bottle in Spanish) is the local name given for this crystal form.
Emerald 'botellas' are only seen in La Pita.

I don't know what's the growth mechanism that triggers this crystal form.
Any idea?

[Fiebre Verde]

20+ aggregates of dioptase-green emeralds crystals.
Matrix is a fine-grained whitish albitite [albitized black shale] which takes the form a stratiform breccia containing some lenses of the original black shale.
In the upper part of the matrix, the red melange partially cemented by pyrite and iron-rich dolomite is actually ankerite (crumbly aspect).
Ankerite is a carbonate mineral which occurs as a product of hydrothermal deposition (and alteration) in the two Colombian emerald belts.
Associated with pyrite, calcite ankerite, on a fine-grained albitite matrix.

[Firmo Espinar]

Hi Gerard.

Congratulations!!

A new blue star for the greenest collection ever seen!!!

Thanks for sharing with us these awesome crystals.

Regards.

[Fiebre Verde]

[Don Lum]

Hello Gerard,

Congratulations on your new Blue Star !

Well deserved and well done.

Regards,

Don

[Fiebre Verde]

[Sante Celiberti]

Chaleureuses félicitations, Gerard.
We all suspect that you would have preferred a green star instead of a blue one. :-)
Warm greetings.
Sante

[Fiebre Verde]

[Philippe Durand]

well done Gérard. your collection is great by aesthetic and by knowledge on this specific green topic