FMF - Friends of Minerals Forum, discussion and message board

[John Williams]

Hi Guys
I live near Baza in Spain and have collected material from Oficarsa Cantera[the Oficarsa Quarry] at Carchelejo for a couple of years.
Can anyone tell me the full suite of minerals found for that site and how to identify them
There is ,of course, prehnite, calcite and epidote.
I also believe I have nice specimens of actinolite-acicular, light to dark green crystals and bissolite?- a hairy green mineral.
Cheers
John Williams

[Jordi Fabre]

It is not Actinolite but Augite (excellent Augite by the way).

In the Spanish magazine Bocamina you can found all details about Carchelejo and their minerals in this great article: https://www.bocamina.com/esp/n16/carchelejo.pdf

Jordi

[John Williams]

Thanks Jordi
Is the hairy green mineral bissolite-I haven't got a copy of Bocamina to hand?
Regards
John

[Jordi Fabre]

Actinolite (Byssolite) is not mentioned as a species in Carchelejo, but it is very common in the Spanish ophiolitic rocks, so why not?.

BTW, why you don't publish a photo here? it could help a lot...

Jordi

[John Williams]

OK Jordi
I'll try and get a few photos on the forum.
Regards
John

[John Williams]

Here is a photo of the pale green hairy mineral, which is possibly a form of augite?

[keldjarn]

Thanks for the informations about other minerals from Carchelejo. I have a nice prehnite from there and it is interesting to note that the paragenesis is very similar to many other localities with good prehnites around ther world in similar rocks.
It is basically the same chemical elements forming pyroxenes (like augite) and amphiboles (like actinolite or "byssolite"). It is very common in the same deposits to find earlier formed pyroxenes and later crystallized amphiboles - often in cavities and on the surface of or protruding from the pyroxenes. Pseudomorphs of amphiboles after earlier formed pyroxenes are also common both as a rockforming mineral and in crystallized specimens (a variety sometimes called "uralite").
Based on your picture it would be reasonable to assume that the hairy mineral is an amphibole which you could call "byssolite" most often corresponding to the mineral actinolite.
Knut

[John Williams]

Many thanks, Knut, for your information.
I also have several specimens with white lath-like groups of crystals ,from Carchelejo, which do not react to acid and are therefore not calcite/dolomite- any ideas. Again I will supply a photo if required.
Regards
John

[keldjarn]

Hello John, a photo would be of great help. Maybe it rings a bell.

Knut

[John Williams]

Thanks Knut
I'll put one on tomorrow.
Regards
John

[John Williams]

Here are two photos of the unknown mineral. Could it be albite or a zeolite of some type?
Or maybe a pseudomorph of some mineral?
Cheers
John

[Jordi Fabre]

I'm sorry John, but by the photo I'm not able to help. Could you do a closer photo?

Jordi

[John Williams]

Ok Jordi
I'll put another closer photo on the forum tomorrow.
Regards
John

[John Williams]

Here is a closer photo, I'm afraid it isn't very sharp, even though I used macro on the camera.

[John S. White]

It is diffficult with such a poor photo but my guess is that these crystals are albite. There is a locality in Pennsylvania, an igneous rock with miarolitic cavities. The suite of minerals in these cavities looks identical to the specimens shown in John Williams' photos, and there are albite crystals which closely resemble these unknown crystals.

[John Williams]

That was my thinking John. Sorry about the poor photo, I get trouble getting sharp images with my Nikon 5600 Coolpix camera at macro distances?
Regards
John Williams