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Improving Mindat.orgYellow Chrysocolla (again)

17th Mar 2016 18:28 UTCJeff Weissman Expert

This image - http://www.mindat.org/photo-737016.html

SInce it is yellow/amber and not blue to green, how do we know this is chrysocolla and not just some silica-gel?

17th Mar 2016 18:59 UTCUwe Kolitsch Manager

I'd ask him. I'd guess it's just visually identified.

17th Mar 2016 22:03 UTCPaul Brandes 🌟 Manager

If nothing else, it's a very nice photo! :-)

There is yellow chrysocolla out there, but it is quite rare....

18th Mar 2016 09:18 UTCYannick Vessely Expert

it was just visually identified.

since I made the picture, "cristals" broke

so I made an acid test on similar crystals, and it is silica -gel

18th Mar 2016 14:53 UTCUwe Kolitsch Manager

Thanks for updating, Yannick.

2nd Nov 2018 04:11 UTCAlix Julien

English:

Hello everyone.

I was wondering why do you call it "silica gel"?

And, in the case of Villecun precisely, why do not you call it Quartz var. Calcedony rather? It will be more consistent with the nomenclature of the IMA, right?

Thank you.

P.S .: Villecun is not quite the town where we find the famous Cuprite var. Chalcotrichite according to the maps. The basaltic part is on Le Puech and the part with Quartz and Azurite (not pierced by the basaltic casting) is on Villecun. Should I open a new discussion to clarify that?

----------------------------------------------------------------------------------------

Français:

Bonjour tout le monde.

Je me demandais pourquoi appelle t'on ça "gel de silice"?

Et, dans le cas de Villecun justement, pourquoi n’appelle t'on pas ça Quartz var. Calcedoine plutôt? Ce serai plus conforme avec la nomenclature de l'IMA, non?

Merci.

P.S.: Villecun n'est pas tout a fait la commune où l'on trouve les fameuses Cuprite var. Chalcotrichite d’après les cartes. La partie basaltique est sur Le Puech et la partie avec du Quartz et de l'Azurite (non percée par la coulée basaltique) est sur Villecun. Faudrait t'il que j'ouvre une nouvelle discussion pour éclaircir ça?

Alix JULIEN, le 02/11/2018

22nd Dec 2018 19:33 UTCRalph S Bottrill 🌟 Manager

Opal?

And what is the orange mineral?

23rd Dec 2018 00:26 UTCAlix Julien

I do not believe in Opal. Just "Silicon gel" (/ chalcedony? :) according to the experts of this material.

By cons, the mineral below is the same thing but an older generation.

Alix JULIEN

23rd Dec 2018 15:31 UTCPaul Brandes 🌟 Manager

Alix Julien Wrote:

-------------------------------------------------------

> I do not believe in Opal.

Care to elaborate on this?

23rd Dec 2018 21:38 UTCRalph S Bottrill 🌟 Manager

Silica gel, chalcedony and opal (several distinct types) are all very different materials in their crystal structures and water content, have a read up on Mindat, Wikipedia or any good mineral book. Not to say that they cannot all form from a gel.

5th Jan 2019 07:10 UTCAlix Julien

Hello. I'm back! Sorry for not being able to answer right away.

I did not dare to speak on the subject because I am not an expert but I wanted to at least report to you what was reported and what I gathered as information (and it is long :). As I said, there is some "experts" who says that it is silica gel.

But by force of observation I asked myself the question if it was not rather Quartz var. Chalcedony...

Then the idea of Opal has arrived :)

So I'll explain to you in more detail why, for me, it does not seem like that (be indulgent):

-In first, when you talk about Opal it's Opal-AN (/ Hyalite) (3-8% water)? Because it's in a matrix of basalt?

-By staying on this idea, it is possible to find Opales-AN in the Hérault (the department) because of its past a little volcanic. I have specimens found at several dozen kilometers from Villecun: a Caux: https://www.mindat.org/loc-271810.html

-But the crystallizations are totally different from Villecun.

Opals are well formed (and bigger in size) and as translucent as water. Then she does not line all the vacuoles but, on the contrary, it looks like she avoids it.

Then, under the microscope Opal is much smoother than the crystals of Villecun ...

- Do not forget that here, in Villecun, it is a vein of Quartz Cupriere (+ Pb, Zn, As, Sb, Fe) which was pierced in surface by a basaltic lift. As a result, all the Copper (and other elements) are "cooked" in the basaltic vacuoles forming Cuprites (+ var., Chalcotrichite), Malachites and others.

But what does the Quartz produce when it is "cooked" in basaltic vacuoles like that... ??

I was a little afraid to say all this because these are only visual observations and in this case, even if it can be learned from things to people, it may not help .. (in any case it does not bring any irrefutable proof I believe)

What type of analysis could allow us to have a precise and irrefutable answer (in order to differentiate Opal-AN, Quart var Chalcedony or others ...)?

(I want to try the American ad for analysis on Mindat's advertising banners;) I need to see if the shipping cost is not too expensive. But it makes you want! )

Thank you all for your interest in the position.

Happy new year to all and best wishes. May this year be full of beautiful finds for you!

Alix JULIEN

5th Jan 2019 08:07 UTCAlfredo Petrov Manager

Alix, when you ship samples for x-ray diffraction analysis you don't need to worry about cost, because a package is not necessary, just a few crumbs (totalling perhaps the volume of half a grain of rice), which can be sent in an ordinary thick envelope, as a letter, which should cost less than 2 euros.

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