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[John Williams]

Hi there
I recently collected specimens from the above mine and thought there was just hemimorphite and goethite present. Having checked on mindat they mention also chalcophanite, which seems to look very similar to goethite in botryoidal form.
Can anyone tell me how to identify the chalcophanite and how it differs from goethite at this site?
Regards
John

[Cesar M. Salvan]

Indeed, there is chacophanite in Precaucion mine. Is common, associated with calcite and hemimorphite.
Is common also the occurrence of chalcophanite included in calcite crystals, forming beautiful botryoidal growhts.

Is relatively easy to identify the chalcophanite of this deposit. Usually is grey, greyish-black or black in color, dull. If you test a small quantity of chalcophanite powder on a microscope slide with a drop of HCl and heat slighly, you can easily smell the evolved chlorine. Also, if you test the powder with hydrogen peroxide, the chalcophanite decompose it evolving oxygen, while goethite is less reactive or do not generate oxigen at all.

Hope to help you

[John Williams]

Thanks for that Cesar.
John

[Cesar M. Salvan]

you´re welcome, John.

Here is an image of hemimorphite with chalcophanite from Precaucion mine. I will try to do a better one and more informative.