Basement Minerals

I was going through some egg cartons with silver from Cobalt, Ontario that I had stored in the basement (60-70% humidity) for 3 years and discovered something had grown on one specimen. The crystals are thin as tinsle ( and flexible) and very shiny up to .75mm long in radiating groups up to 1.5mm wide. Anyone have any ideas what these might be? The specimens had only been washed in water ( 3 yrs ago) and consist of wire silver with a small amount of some sort of fine grained arsenide on one end from which the crystals have grown. My guess is xanthoconite based on the color and form? Also would this be a valid mineral species?



Edited 1 time(s). Last edit at 08/17/2011 07:03PM by Reiner Mielke.

> Also would this be a valid mineral species?

sadly not by current official definitions. But how you choose to classify it is entirely up to you! Nice find.

The colour is OK for Xanthoconite but the habit is not convincing. Perhaps an arsenate of some sort?

I'll send it off for EDS analysis. The crystals are very thin and the slightest breeze causes them to shake.

Are you absolutely sure that the crystals were not there when you put the samples in storage? Perhaps you did not notice them.

Absolutely certain they really stand out. Besides they are far too fragile to have possibly survived a washing.



Edited 1 time(s). Last edit at 08/29/2011 01:24PM by Reiner Mielke.

Shows where my mind is.
When I saw "Basement Minerals", first thing I thought of was the crystalline rocks/minerals of the Canadian Shield..... B)

Now I know that anything resulting from "human activity" is not considered a mineral. My question is: if a secondary compound is formed when a mineral formed deep in the crust is brought to the surface and exposed to air and water, does it matter if the original mineral was brought to the surface by faulting and erosion or by human mining? The chemical history of the new compound is the same. This is especially true if the "human activity" is not obvious. Something formed in slag or a coating on an old bullet is one thing, but this is really a different case.

Feathery Acanthites often form on Beaverdell Ag minerals. If this happens in rock the Acanthite is a mineral. If it happens post mining it is merely cabinet growth and not a "valid" mineral. There is absolutely no difference between the mineral and the cabinet growth.

We seem to be starting a new geologic age with human intervention and when this is accepted maybe the IMA will accept anthropogenic artifacts as minerals.

It may be Claudetite.

Uwe Ludwig

Can't be claudetite (which is colourless or white).

Drawing the line between "natural" minerals and anthropogenic substances is not easy. Post mining compounds formed on untreated dump material are considered valid mineral species.
I will, on purpose, place boulders rich in REE-minerals on the seashore, and return in some years to look for new minerals with REE, Na and Cl...

Yes Uwe, normally Claudetite is colourless. However, the pieces have been treated before storing and who knows the conditions in a humid basement? I saw a lot of coloured minerals which are normally colourless. According to my opinion the colour is no certain criterion of a mineral.

Uwe Ludwig

Are claudetite crystals (colour notwithstanding) generally tinsellike and flexible as described?

Claudetite is not always colourless (see ID 348684 and ID 348680) and it is soft and flexible according to the literature I read.

Uwe Ludwig

Hello Tomas,

Great idea, I think I will start a mineral garden in my backyard.

About twenty years ago I put some mercury into an aluminium can with a screw top, then last year when I found it in my shed I opened it, and found to my surprise that there was no mercury left, instead there where several shiney silvery-grey crystals, could anyone tell me what has gone on here, and what the crystals might be?

email address.........garnets@hotmail.co.uk

Thank you. Spencer.

Aluminium amalgam has formed, I suppose? Lovely find, in crystal form!

But since you've opened it and exposed it to the air, it will get destroyed - Seal it up again, quick!

Hello Spencer,

Take a picture so even if it gets destroyed you still have a record of it, would love to see it.

Got the EDS results back, looks like it is acanthite! But it is transparent!!! Could it be a silver sulphate?



Edited 2 time(s). Last edit at 09/21/2011 12:52AM by Reiner Mielke.