Geochemistry, Mineralogy, Petrology & Volcanology

#mineralmonday : sengierite

#mineralmonday : sengierite

#mineralmonday: your weekly* dose of obscure mineralogy, every Monday** [*not guaranteed; **or possibly Tuesday-Sunday]

What is it? Sengierite: Cu2(UO2)2V2O8.6(H2O)

What’s it made of? A few useful metals – copper (Cu), vanadium (V), uranium (U), plus oxygen (O) and water (H2O).

So by ‘useful’ you mean ‘radioactive’? Pretty much. The main reason people have been interested in this kind of mineral is the (very radioactive) uranium, which is important for nuclear power and military uses. The copper (not radioactive) is also useful though – this is a secondary mineral that is often found in mines where copper and uranium are extracted together.

Sengierite, from Leon Hupperichs via

Secondary mineral? Like second class? That seems harsh. Basically, primary minerals are the ones that form when the rock is forming in the first place, so if the rock is crystallising from a liquid or magma, the minerals that form at that point are primary. If this rock then gets weathered, or maybe some water passes through it, new minerals can sometimes form – these are the secondary minerals.

I see, so it’s more like an caterpillar becoming a beautiful butterfly? Something like that. These secondary minerals are often hydrous, meaning they have water explicitly in their structure. That doesn’t mean the mineral is just wet, but rather there is a specific place for the water in the lattice of atoms. You can see this is the case for sengierite because of the 6(H2O) at the end of the formula.

So is it pretty? Absolutely. This one is a beautiful bottle green to apple green colour. It also has what we call a vitreous to adamantine lustre (lustre describes how light interacts with the mineral – vitreous is kind of like glass, adamantine is like a diamond). Probably best to avoid radioactive crystals for use in jewelery though…

Do you have a favourite obscure mineral? Want to write about it? Contact us and give it a go!

Mike Jollands is an experimental petrologist at the Lamont Doherty Earth Observatory, New York, USA. He studies the diffusion and substitution mechanisms of trace elements, making use of high temperature and pressure equipment to simulate volcanic and mantle conditions.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>