Is Your Rock Not Of This Earth? Meteorite Hopefuls Seek Answers At ASU
Meteorites fall evenly all over the Earth, but with little rain in the Southwest, the extra-terrestrial rocks last longer in this part of the world. But if you aren't sure what you picked up is simply construction debris or from another world, an Arizona lab can help you find out for sure.
On Nov. 7 at ASU’s Earth and Space Exploration Day, a line formed in front of Cameron Mercer, a doctoral student in planetary geology. He helped people figure out if the rocks they had in hand are from Earth or elsewhere — but Mercer found a lot of the same material.
"I think a lot of it is slag from mining pits," said Mercer. "So there’s been a lot of hunting for mineral deposits throughout Arizona and then often times they smelt down little bits of ore and you get these leftovers. And if somebody is walking out in the desert and finds that it looks really weird, and it's because it’s been processed artificially.”
One of the hopefuls in line walked up with two samples in hand.
“I don’t think so, no," Mercer said. "This is kind of some caliche from the desert probably. Some kind of limestone. And this is probably, well, it could be volcanic. It looks, so this might be a volcanic rock. It’s not as heavy as I might expect it to be. And then it’s not magnetic at all."
Mercer said that all meteorites are magnetic because they contain iron and nickel. Along with a magnet, he had a few items in front of him to test the samples that people bring in. There was a plate of glass to see if the samples can scratch it to measure hardness, and a ceramic plate to see the color streak, as most Earth minerals leave behind a reddish streak.
Another ASU scientist hovered over a sample in the hands of an older gentleman that has two small magnets firmly in place.
“Feel this weight first," said Ron Deplazes. "That’s what brought our attention. Now try and take one of them magnets off of it.
Deplazes grinned as I struggled to remove a magnet shaped like a pencil eraser.
“So that’s what I’m saying, it’s got some real metal in it,” Deplazes said.
Deplazes said he found the sample with his son when they were walking near Central Avenue and the Salt River.
“And he seen this stone laying there and he picked it up and naturally if you feel it, the weight, is what started our interest in it,” said Deplazes.
And it got Laurence Garvie interested in the rock, too. He’s with ASU’s Center for Meteorite Studies and thinks this sample needs to be brought in the lab for further testing.
“I can’t rule this out as a 'meteowrong,' just because it is a little bit unusual," said Deplazes. "Now, I don’t think it’s a meteorite just because one surface is too flat. And I have seen an industrial material that does look like this. But sometimes, like this particular thing, it would require further investigation.”
Garvie invited us down an adjacent hallway.
“Now, we’re going into somewhere that almost no member of the public gets to go into,” Garvie said.
We headed into ASU’s meteorite lab and vault. It’s behind both digital and manual lock and key. “This is the largest meteorite collection in a university in the world," said Garvie.
There are beautiful samples of meteorites everywhere. Cross-sections of specimens have a molten like outside but a sheer crystal-like metallic face, showing intricate patterns of metals. Garvie pointed out a recently received sample.
“You know, science hasn’t determined what this thing is but we know it’s meteoritic," said Garvie. "Every meteorite tells us a story, and so part of our job as scientists is to put the little bits of information together that we get from each meteorite to sort of complete that early story of our solar system.”
Garvie took Deplazes' sample and brought it over for further testing to see if it is a meteorite.
“To figure out what’s going on inside, I think we have to grind a bit of the exterior to have a look," said Garvie. "I’m going to use some water as the lubricant, and I just got a grinding pad on here so we’re just going to grind a small corner of it, and see what we see. You see bit of the metal coming off of it. Oh look at that, isn’t that beautiful. Look at that you can see the beautiful millimeter, submillimeter size spheres, spheres of metal. Now since it’s magnetic it’s almost certainly iron, I think this is some compressed, man-made metal object. Most of the spheres are about the same size as well. This is obviously just a slice.”
“And all these little piece are all metal?" asked Deplazes.
“All the shiny stuff is just metal. And then there are some darker silicates in there as well. So, I don’t think it is but it is one of those things, you know, just don’t know until we do some more testing,” Garvie said.
So, next time you kick a rock that seems a little heavier than it appears, hold onto it. Although you’ll have to wait until next year to test it, it just may just be from out of this world.