The world's oldest rock is punny

I finally found time to read the paper describing the new World's Oldest Rock. I wanted to blog about why news reports seemed cautious about trusting its age (for instance, see Richard Kerr's write-up in Science). I need to spend more time thinking through the isotope geochemistry of the heavy rare-earth elements before that's possible, unfortunately. (Maybe a fan of extinct isotopes could help, since the argument is based on decay of 146Sm?)

But the problem, really, is that I got distracted by the mineralogy of the gneiss in question. The rock is described as a "faux-amphibolite," and is made of plagioclase, biotite, quartz, some garnet, and...

...wait...

...cummingtonite.

That's right. The world's oldest rock contains one of the favorite minerals of dirty-minded geology majors.

Other discussions in the geoblogosphere:

The Volcanism Blog
NOVA Geoblog
goodSchist (Chris mentions familiarity with the 146Sm-142Nd system; maybe he could help evaluate the paper)
olelog
About.com geology

(And they did a good job of linking to discussions in the media, so I won't try.)

Night of the living superprobe?

I just got yet another Nigerian scam e-mail:

FROM THE DESK OF ZOMBO JEOL

And I thought... you know... I always wondered whether the microprobe was a zombie. All those late nights in the dark, eating my brain...

Good thing the lab I'm using now has a Cameca.

Love Letter to a Piece of Schist

Note: I was trying to think of something appropriately geological to write for Valentine's Day, and this is what came out. You have been warned.

Look. You were hot. Once. Maybe more than once. And when everything was in equilibrium, well, you were a thing of beauty. Your micas had that sparkle, and your andalusite was a porphyroblast. And when your garnets rolled, baby, there was nothing to do but watch your inclusion trail.

But let's face it. You were never particularly gneiss, and everything's cooled since then. Don't tell me that your textures have gotten complicated - you've retrograded. Your reactions are incomplete. You're retaining too much argon.

I changed you. And I suppose that's what I get for letting you take me for granite.