I’d like to thank the alaskademy

It looks like the generous allochthonous Alaskan who blogs as Wayfarer Scientista has given me the Brilliante award. Presumably, this is some sort of baddeleyite allotrope.

Baddeleyite, formula unit ZrO₂, is a great mineral, so it is a shame that synthetic cubic zirconia has a higher profile in the more colorful parts of non-geologic human culture. Of course, the trick to getting ZrO₂ to grow in a cubic structure is itself interesting- it seems that cubic zirconia is in fact a Zr-rich tazheranite solid solution. But growing big crystals at all is impressive when you consider that zirconia has one of the highest melting points of any known substance. But enough of this lapidarial digression.

In order to crystallize baddeleyite, two conditions must be met. Firstly, the major minerals must be saturated in Zr. Secondly, the SiO₂ activity has to be low enough that zircon doesn’t grow. This makes the mineral somewhat uncommon. Never the less, it does have a high U/Pb ratio, so it is used for geochronology for rocks that don’t have zircon.

Interestingly, metamorphic fluids are often silica rich, so in some altered rocks a zircon reaction rim will grow on a baddeleyite, allowing both the crystallization age and the alteration age to be determined. In practical terms, this means that if you want a good date, then natural, monoclinic zirconia is more reliable than its artificial, cubic allotrope.

Evidently I am supposed to pass this award along, so nominate the following blogs as being cubic zirconia-worthy:
The Planetary Society Blog
Molecule of the Day
This non-American Life
Apparent Dip
The Volcanism blog
All my faults are stress related
And if any of y'all have already been awarded, then give yourselves an allotrope instead.

Isotope Park

When it comes to extinctions, animals are extremely over-represented in the public eye. Everybody knows what a dinosaur is. And most people have heard of trilobites. But seed ferns? Not so much. And when it comes to nuclides, the lack of public recognition is even more severe. When’s the last time your non-geological friends told you their 6 year old loves ⁶⁰Fe?

I would like to correct this. Extinct nuclides are vital to our understanding of the solar system, and are every bit as deserving of popularity as a triceratops. I consider this to be an injustice, a disgrace. I will not be satisfied until Hollywood blockbusters have Laura Dern fleeing in terror, as a pack of angry- and radioactive- molecules of ²⁶Al¹²⁹I₃ come chasing in pursuit.

But before this dream can become a reality, I should probably explain what they are.

Extinct nuclides are radioactive isotopes that no longer exist in detectable quantities in the modern solar system, but whose presence in the early solar system can be deduced from their decay products. A table showing several geologically interesting live and extinct isotopes is shown below, with a logarithmic timescale at top.

Extinct nuclides are valuable for establishing timelines for the first 1-50 million years of the solar system’s history. This is the time during which the protoplanetary disk cools enough to start condensing crystalline matter, and this matter then forms condrules, asteroids, planetesimals, and eventually, the terrestrial planets that we know and love today. It is constrains from these isotopic systems that tell us the chondrites and apparent bodies for iron meteorites formed in the first few million years, while the time required for these planetesimals to collide and form the four inner planets was about ten times as long. This is all a result of painstaking isotopic analysis and interpretation using a fairly simple theory. The story goes like this:

Once upon a time, there was a giant molecular cloud. One day, a nearby star exploded in a supernova. This supernova created lots of R-process and P-process nuclides, including all the short lived ones. The shockwave triggered a collapse of the molecular cloud, and initiated the formation of the sun and the rest of the solar system, with all these newly formed nuclides mixed in. The radioactive ones decayed, but the stable ones lived happily ever after.

At least, that’s what we geochemists thought. Unfortunately for us, a gang of tactless astrophysicists crashed our storytime party and spewed numerical garbage all over our tidy white cleanrooms. But that is a discussion for another day.

Love and loss at one and a quarter

Look daddy!

A balloon!

Watch me practice sitting...




I am so proud that she didn't cry.

Fifty great minerals

For the last 34 million years, the “50 great books” meme has been polluting the otherwise focused blogosphere. More recently, knockoffs such as the top 7.5x10¹ - 10³ popular science books, or the top foods list have been appearing. As a geologist I am mortified that such frivolities should appear when there are much more important things to put in fanciful-yet-judgmental bandwagon lists. I mean, let’s be honest here. Books and food comprise a volumetrically insignificant part of this planet’s mass. If we want to list something substantial, we should to isotopes. Or rocks. Or minerals.

So without further ado, here is the list of 50 minerals that everyone should see.
Use bold to indicate minerals you’ve seen in the wild. Italics is for those seen in laboratories, museums, stores, or other non field locations. Ex pet nerds may use underlining to indicate those that they’ve grown with their own two hands. And I won’t bother with stuff you intend on seeing- if you didn’t want to see all these minerals yourself, you’d be spending your precious lunch hour on a physics or biomedical blog.

50 minerals everyone should see:
Andalucite
Apatite
Barite
Beryl
Biotite
Chromite
Chrysotile
Cordierite
Corundum
Diamond
Dolomite
Florencite
Galena
Garnet
Graphite
Gypsum
Halite
Hematite
Hornblende
Illite
Illmenite
Kaolinite
Kyanite
Lepidolite
Limonite
Magnetite
Molybdenite
Monazite
Nepheline
Olivine
Omphacite
Opal
Perovskite
Plagioclase
Pyrite
Quartz
Rutile
Sanidine
Sillimanite
Silver (native)
Sphalerite
Staurolite
Sulphur (native)
Talc
Tourmaline
Tremolite
Turquoise
Vermiculite
Willemite
Zeolite
Zircon

Carnival of Space 59

This week, the carnival is an alphabetical rhyme.

Culturally sensitive sexism

In these days of reconciliation, it seems that being a sexist prick is no longer exclusively the privilege of crusty old white guys. According to the news this morning, aboriginal academics are calling for a book to be pulped because it encourages girls to play the didgeridoo. Says Mark Rose, general manager of the Victorian Aboriginal Education Association:

"I reckon it's the equivalent of encouraging someone to play with razor blades. I would say pulp it."

The Inner Solar System

The stellar system hosting this blog is characterized by two gas giants and two ice giants. These four bodies constitute 99.5% of the planetary mass of the system. However, there is a small amount of rocky matter orbiting close to the star Sol, which accreted in an area too warm for the ices to condense into proper sized planets. Although this part of the solar system is dynamically insignificant, great importance is placed on it by a particular species of bipedal mammal, as these creatures are unfortunate enough to live on the largest of these rocks. In the following picture, all three other planets and the planet-sized moon of the largest object can be seen behind the clouds of this largest inner planet’s atmosphere. Readers interested in the relative mass of these planets are referred to the rocky planet pie chart. Correct identification of each rock is left as an exercise for the reader.

I hate scientific writing

Activities I consider preferable are:

• Getting knocked off a motorcycle at high speed
• Rolling a kayak with a broken tailbone
• Getting a hostile customs interrogation from drunk border guards

I don’t mind doing posters, and I love talking at conferences. And before I wrote my PhD thesis I actually enjoyed writing non-scientific stuff. And after a few years of post thesis shell shock, one reason I started this blog was to try and befriend words again. But after a month and a half of report writing, I’m having a relapse. So don’t be surprised if substantive blogging tails off. I’ve moved past the procrastination stage to the wimper under the desk stage. I don’t even have the motivation to ink a cartoon, which would let me post with no words at all. Goodnight people.