Geochemistry, Mineralogy, Petrology & Volcanology

Geochemistry, Mineralogy, Petrology & Volcanology

#mineralmonday: lazurite

#mineralmonday: lazurite

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

What is it? Lazurite. Take a deep breath, the formula is Na3CaAl3Si3O12S.


Lazurite, from Didier Descouens via

That’s a lot of elements to digest, what does it mean? Well, the aluminium (Al) and silicon (Si) form tetrahedra (4-faced 3D triangular shapes), with oxygen (O) on the points. These are arranged in rings with the sodium (Na) and calcium (Ca), with the sulphur (S) sitting in the middle. This kind of structure is called a cyclosilicate, because of the cyclical (ring shaped) arrangment.


OK now I’m bored. Is it pretty? Not just pretty – but pretty on a biblical scale. Lazurite is what makes lapis lazuli blue – this has been a semi precious stone for thousands of years. It’s basically lazurite with a couple of other minerals (we’ll get there another day). Here is a shout out from the Old Testament (Exodus): “Under his feet there seemed to be a surface of brilliant blue lapis lazuli, as clear as the sky itself“.

Alright I’m sold, where can I get some for under my own feet? The main worldwide source of lapis lazuli, and hence lazurite, is a mining district in northern Afghanistan. It’s been mined through the times of the Greek, Roman, Mesopotamian and Egyptian empires. As well as being used for carvings, jewelery and apparently flooring, ground up lapis lazuli / lazurite was used for making the colour ultramarine, widely used by painters in the Renaissance.

Girl with a Pearl Earring, aka Girl with a Lazurite Blue Headscarf, made from natural ultramarine.

If more minerals were blue then geology would be way more interesting, right? Probably. There are only so many ways we can describe the colours grey and brown when looking at rocks. The colour comes from the sulphur, but exactly how the sulphur relates to the colour is still apparently up for some debate.

And who or what is lazurite named after? Simply, named for the colour blue. In Persian, this is lāzhward, which was originally the name of the place where the blue lapis lazuli stone was mined, which then ended up being used to describe the colour itself.

So the mineral was named after the colour, which was named after the town, which was named after the stone. I’m confused. Me too. It’s like time travel movies. Don’t think about it too much.

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

Seven reasons why YOU should propose an EGU 2020 session

Seven reasons why YOU should propose an EGU 2020 session

Did you ever notice that the majority of convenors of the EGU conference sessions seem to be older than you? Have you ever despaired that none of the conference sessions are directly relevant to your work? Does your CV look conspicuously blank in the ‘Service’ section? Have you ever tried to sneak one of your friends into the EGU Friday night party only to be discovered, have your conference name badge (and the public transport pass) ripped up, then have to buy a metro ticket to get back to your apartment, and then eaten a takeout pizza alone while all your friends are having a great night?

It doesn’t have to be this way! It’s the Early Career Scientists (ECS) who provide the much of the engine for scientific research, and we can be the drivers too. So why should you consider a session proposal?

  • You can have some control over the content of the conference

What’s the best way to make a conference really relevant to you? Organise it yourself!

  • The EGU wants you to do it!

Mike Burton (2019 outgoing GMPV President): “Promoting the science and development of ECS is a key priority of EGU and therefore session proposals led by ECS are always welcome.

  • Your session proposal doesn’t quite fit the section? You can cross list with other themes!

Maybe you have an idea but it’s a little bit petrology and a little bit tectonics? No worries, you can list in multiple themes. Not only does this broaden your scope, but it will increase your visibility among people you may not know at all!

  • It’s a nice way to meet new people

It’s a great way to network, and to be the first to hear about what all your colleagues are doing. Not only will you get to know other people, but other people will get to know you!

  •  It’s great for your CV, and for the community

The community only works because people serve it, and this is reflected in CVs. Daniela Rubatto (2019 Bunsen Medallist) says: “Service to the community is a big part of any CV, and conference organisation is some of the most important service you can do”.

  • The conference organisers take care of most of the admin, you just look after the science!

Your job is to propose the session, then promote it among your peers. Then if you have enough submissions to make a session, you get to decide who gets an oral presentation and who gets a poster (the EGU considers them equal). You don’t have to worry about finding a room, hooking up a projector, realising that the projector doesn’t work with Apple computers. Just relax and convene!

  • There is a party on Friday night for convenors

Anonymous : “The Friday night party is really good fun. Getting to the airport or train station the next morning is not”.

#mineralmonday : emmonsite

#mineralmonday : emmonsite

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

What is it? emmonsite, Fe2Te3O9.2H2O

Emmonsite from Moctezuma Mine. Photo by Leon Hupperichs, via

What’s it made of? Iron (Fe), tellurium (Te), oxygen (O) and water (H2O)

I think I remember tellurium from chemistry class – remind me what it is? We can more or less divide the elements into the metals and the non-metals – tellurium is one that sits in between the two groups – it’s a ‘metalloid’. It’s recently become really important for making solar panels.

So can we mine the emmonsite? Actually, the main source of tellurium for solar panels is a by-product of copper refining – this provides about as much as we need at the moment. And also, emmonsite is really rare.

That’s annoying. Is it pretty at least? Yeah, it’s a beautiful apple green mineral that can take different forms – small crystals covering the surface of rocks, little prisms or even some plant-like shapes (see photos).

Emmonsite from Moctezuma Mine, photo by Christian Rewitzer, via

And I guess it’s named after an emmons, what’s that? Samual Emmons – he was an American geologist in the late 1800s. Like Matt Damon, he was from Boston, but quite unlike Matt Damon, the largest glacier in the contiguous USA is named after him (Emmons glacier). Also two mountains (both called Mount Emmons, confusingly).

Seems unfair to have so much named after one person? Yeah. Maybe it’s something to aspire to, but I had a look at google maps and it looks like all the good mountains are already taken…

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

#mineralmonday : gadolinite-(Y)

#mineralmonday : gadolinite-(Y)

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

What is it? Gadolinite-(Y),Y2FeBe2Si2O10

Gadolinite: From Rob Lavinsky, – CC-BY-SA-3.0, via

What’s it made of?: It’s a silicate (a mineral containing silicon (Si) and oxygen (O)) also containing yttrium (Y), beryllium (Be) and iron (Fe). Yttrium is a rare earth element – somewhat of a misnomer as in general they aren’t really that rare.

Is it dangerous? It can contain some uranium and thorium, both of which can emit radiation when they decay to other elements. Probably more dangerous if thrown – it’s pretty dense (about 4x heavier than its equivalent volume of water)

Is it pretty? Not really, unless you like greasy looking, opaque, blackish lumps. No judgement.

What’s it named after? Named after a ‘who’ not a ‘what’ – it was named for the Finnish chemist Johan Gadolin, who discovered yttrium. He also had the element gadolinium named after him.

Johan Gadolin, seen here in his natural habitat on a postage stamp. Source:

Wait, so why didn’t they name yttrium after him? Well, ten years earlier a sample of an unknown rock had been found at Ytterby in Sweden, and named for the village, the name more or less stuck when Mr Gadolin identified what it was.

Do any non-Scandinavian countries get to be involved? Not really – much like the Eurovision song contest, the Scandinavians had a near complete monopoly on the early research into the rare-earth elements.

We are getting sidetracked here, why should we care about this mineral? The whole group of rare earth elements are becoming really important these days – we need them for loads of modern technological uses, but some of the most important are rechargeable batteries, really strong magnets, etc. The looming threat of a trade war between the USA and China, who currently hold the vast majority of the world’s supply of these elements, will only make people more interested in minerals that contain them.

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