That Age-Old Problem...

Mineral Matters #419

Mineral identification.

Minerals can be complex beasts. Even mineral species that are common, and supposedly easily identifiable by visual means, may not be what they seem. Take pyromorphite for example. How sure are you that it is pyromorphite? It could be mimetite. Colour isn’t definitive. Are you sure of the locality information?

Most collectors rely on one of two things. Either mineral recognition - I have seen this mineral before from this particular locality, and am pretty confident that it is “X”. Or, that is what is on the label, and I am comfortable with the dealer’s knowledge or access to testing the specimen. The latter is particularly the case for rare species.

This particular specimen is a case in point.

Gunnar Färber is a specialised dealer. He specialises in rare species. He has been around for a long time and has access to his own analytical processes. I bought this specimen many years ago for the locality, as much as for the “species”. And trust the identification as it is from Gunnar. I have no reason not to.

Note I said “species”. Isoclasite is a valid species but marked as questionable by the IMA (it applies to poorly characterised minerals, whose validity could be doubtful).

I uploaded the photo to Mindat, but it is marked as “Pending approval” as I can’t provide evidence of its validity. Gunnar does not include how he determined it on the label. Note that Gunnar still offers samples of this mineral.

So, the questions for you, dear readers, are:

• Do you trust your ability to recognise species?

• Do you trust the details on the label you got with the specimen?

• Do you submit your specimens for analysis?

Let me know in the comments.

Below: Isoclasite and fluorapatite, South Point, Flying Fish Cove, Christmas Island. Width of view 9mm. Click on the image for a higher resolution version.