I am reading about the mineral zircon.
Sounds like an evil science-villain from a pulp serial, doesn't it! ZIRCON THE DESTROYER, galactic space-emperor!!!! It is not, I found, the same thing as cubic zirconium, the diamond substitute, which is ZnO2, zirconium dioxide. No, the zircon I'm talkin' 'bout is ZrSiO4, zirconium silicate, and apart from the action-adventure name, here's why it's so cool.
Zircon is the oldest known mineral on earth. This is because it is the very first thing to crystallize when molten granitic magma cools to the point where solid crystals are even possible. Then granite forms around the zircon crystals. However, zircon is harder than granite, a 7.5 on the Mohs scale (1 = talc, 7 = quartz, 10 = diamond). Thus this oldest granite part of Earth's first crust eroded away, leaving the zircon crystals to stand as our only relic of the first-ever surface of our planet! Planet Earth's oldest minerals!!! How cool is that???
It gets even better.
We are using a tiny FLECK of zircon crystal from Apollo-freakin'-17 to help us fine-tune date the age of the freakin' MOON!!!
HOW AWESOME IS THAT??? :) :) :)
Here's my utterly sleep-deprived, exercise-sore, underperkilycaffeinated understanding of how it works. Please feel more than welcome to correct me in the comments if I've fluffed it!
To date, our analyzed lunar samples had been from low-lying areas of the moon, which had suffered meteor impacts, and thus the crust had re-melted. Thus, these zircons were younger than the formation of the moon. The fleck, half a millimeter in diameter, which will hence be known as THE FLECK, came from the lunar highlands, and is 4.42 billion years old! That's TWO DECIMAL POINTS, BAYBEE!!!! In geological terms, that's INSANELY precise! We can date it with this degree of precision 'cause zircon crystals often contain uranium, which of course decays into lead at an extremely regular and well-known rate. So you measure the ratio of lead to uranium inside your zircon, and voila! The age of your mineral. The reason we've never done this precise an analysis before is that our technology has advanced considerably since the time the Apollo samples came back. They've got that hoopy frood Alexander Nemchin, who discovered the world's oldest diamond, working on it! :)
The Moon is generally believed to have coalesced out of the debris when a Mars-sized object BASHED into the Earth back when the solar system was still gettin' its shiznit together. KAPOWWWWWW, SPLAT!!!! Ohhhhh the chaos!!! Cats and dogs living together!!! Mass hysteria! So, the Moon cooled off before the Earth did 'cause it's got less mass, and we know about how long it would have taken a Moon-sized glop of magma to cool off enough to form zircon crystals. So the approximate age of the Moon = the age of the oldest zircon we find there + cooling time. NEAT, huh? :)
Finding THE FLECK, this tiny mote, and with our tools of analysis turning it into such a COLOSSUS OF SCIENCE, is hugely exciting to me-- not just in the results, but in the manner in which we get the results! I LOVE IT when huge discoveries come in teeny, tiny packages!!!
It's one small stone for man, and one giant leap for mankind's understanding.
Memorial Day redux
11 months ago