Iridium and the Periodic Table of Death

In the immortal words of Miss Mona Lisa Vito:

Imagine you’re a dee-ah. You’re prancin’ along, you get thirsty, you spot a little brook.

You put your little dee-ah lips down to the cool clear what-ah…

BAM!

Marisa Tomei received an Oscar for her role as Miss Vito in the movie My Cousin Vinny (1992). Click on the link (1) to watch the whole scene, ‘cause it’s hilarious and hard to write her accent but be warned. It’s NSFW (2).

Now, imagine 66 million years ago, a duck-billed hadrosaur, the dee-ah of the Cretaceous, was prancin’ along, got thirsty, spotted a little brook, and put her little duck-billed lips to the cool clear what-ah, and…

BAM!!

An asteroid as large as 50 miles across hits what we now call the Yucatan, vaporizes in the 20,000-degree heat caused by the energy of the collision, catches pretty much everything on fire for 100s of miles, creates tsunamis as tall as the Eiffel tower, pitches the world into darkness for a year because of debris and dust thrown into the sky, and completely wipes out the dinosaurs. Well, almost completely (3).

Eventually, all that dust in the air had to drop to earth, and this is where Iridium (Ir) comes into play in the death of the dinosaurs and the rise of mammals (including us). Ir is an extremely dense and brittle silver metallic element in the platinum group with an atomic number of 77. It is one of the rarest elements on earth (4), rarer than the rare-earth elements, which turn out to be not so rare, just hard to extract without really messing up the environment (5)(6). It was found as a contaminant of platinum (Pt) and, when pure, it does not oxidize or corrode, thus is used in products where that particular characteristic is important, like spark plugs and … fountain pens nibs? (7) Seriously?

The name Iridium comes from “iridescent” because of the multiple colors it turns when it becomes a salt. The discoverer of Ir, British chemist Smithson Tennant, actually named it after the Greek goddess Iris (8). Iris means rainbow in Latin and Greek, and Iris is the goddess of rainbows (9). Aww…

But when that asteroid hit our planet, it left behind more than just the Chicxulub crater. Everywhere we’ve looked on earth, we’ve found a thin layer of clay at the Cretaceous-Paleogene boundary that has 100 times more Ir in it than the surrounding soil. Below that boundary line are dinosaur fossils, above it, not so much. We also see Ir at much higher concentrations in asteroids and meteorites. So, putting two and two together, the scientist Luis Alvarez came up with the Alvarez hypothesis that postulates an extra-terrestrial cause for dinosaur extinction (10) … all because of the Periodic Table of Death element Iridium.

(Psst. If you REALLY want to know what killed off the dinosaurs, click here.)

As always, these are my own opinions based on my biases, knowledge, and understanding, and the websites I’ve linked are in no way an endorsement.