Deep Mantle Mineral Found in Diamond 

THIS ARTICLE tells us of a newly named mineral found as an inclusion in a diamond. The mineral had been made in high pressure, high temperature laboratories but the authors are among the first to find it in nature and the first to, officially, name it. 

The composition is the same as wollastonite (see HERE) CaSiO₃, and has been called davemaoite. It is thought to be the third most abundant mineral in the lower mantle and is capable of holding various isotopes of uranium, thorium and potassium. And it is these isotopes which generate a lot of the heat in this part of the mantle.

The inclusions in the diamond must be at a very high pressure as the mineral cannot exist at surface pressures. You can make a mineral but you cannot name it as a mineral if it is not found as naturally occurring. Being tiny and in a diamond counts as naturally occurring!

This diamond holds tiny black specks of davemaoite, a mineral formed at high temperature and pressure in the deep Earth. Credit: Aaron Celestian, Natural History Museum of Los Angeles County

Explosive Lake Kivu - an audio long-read 

Lake Kivu has 300 cubic kilometres of dissolved carbon monoxide 60 cubic kilometres of methane! 

You can listen very pleasantly to a long-read from Nature HERE and find out about the science, the business and the politics - nothing is ever easy!

Planetesimals or Pebbles 

How do planets form? For decades, when asked, people like me would mutter something about planetesimals and quickly move on. THIS ARTICLE suggests that the word I should mutter is pebbles. And tell people to read the article!

Apparently there was some difficulty about planetesimals - it would take too long for them to form. A planet like Jupiter would take tens of millions of years to form a core, by which time the protoplanetary disc from which they would need to accumulate gas would no longer exist. Instead of planetesimals, measured in 100's of kilometres, pebbles, measured in millimetres and centimetres, were the answer. And todays telescopes could see them.

  ALMA observations of protoplanetary disk around HL Tauri in 2014 revealed hidden structures, including the presence of pebbles in the disk.

ALMA (ESO/NAOJ/NRAO)

The pebble theory rapidly gained acceptance for the giant planets but it has difficulties for smaller planets like the Earth. The article discusses this and comes to no definite conclusion. I suspect that debate will continue for years and, eventually a consensus will be reached. 

In the meantime the word is pebbles - probably!

 Down to Earth Extra - November 2021 

The latest edition of Down to Earth Extra is HERE.

And you can read it below.  

La Palma Videos 

A correspondent has told me that these three videos are well worth viewing, especially the first and the third. I quite agree!

Eruption Update

The Noisy Volcano

The Lava Delta