Geochemistry, Mineralogy, Petrology & Volcanology

How do crystal aggregates form in magma chambers?

EGU Guest blogger September 5, 2019

EBSD map of chromite crystals colored according to the orientation, showing random orientations.

By Penny Wieser (PhD student at the University of Cambridge) Clues into the inner workings of volcanoes can be gleamed from material which is erupted at the surface, or that which solidified at depth in the crust. Just before eruption, three main phases are present: a gas phase (containing water, carbon dioxide, sulphur, chlorine etc), a liquid melt phase (the magma), and a solid phase (consisting ...[Read More]

#mineralmonday : sengierite

Mike Jollands August 4, 2019

#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 ...[Read More]

Are mantle melts heterogeneous on a centimeter scale?

Mike Jollands July 18, 2019

The mantle makes up the majority of the volume of the Earth, but there is still a lot about it that we don’t understand. This is because we can’t observe it directly – forget ‘Journey to the center of the Earth’ – even our deepest drill holes (about 12 km deep) are merely tickling the surface of the planet (about 6400 km to the center). Most of what we know abou ...[Read More]

#mineralmonday : lithiophilite

Mike Jollands July 15, 2019

What is it? Lithiophilite, LiMnPO4 What’s it made of? Lithium (Li), manganese (Mn), phosphorus (P) and oxygen (O). The PO4 at the end of the formula makes this a phosphate mineral (phosphorus + oxygen = phosphate). What’s it’s structure? The way the different atoms are arranged in lithiophilite is described as orthorhombic, which means the crystal is built of lots of tiny cuboid- ...[Read More]