Rugged Microscopic Minerals

Researchers generally measure certain ###### elements in rocks to figure ###### how long a rock has ###### around. But when the meteorites ###### into Earth, that melts the ###### down and can erase the ######.
That's why scientists picked the ###### baddeleyites: Once they form, they ###### durable little minerals. It's not ###### to melt them down. By ###### at the radioactive uranium and ###### in this tough rock, the ###### found that it formed sometime ###### 187 million years ago.]]> The scientists could also ###### evidence of the damage done ###### the meteorite by whatever event ###### it shooting off the Martian ###### around 22 million years ago. ###### shock had muddled up the ###### structure inside, though the chemicals ###### were mostly unchanged. The result ###### something like shaking up a ###### gift box of chocolates.
"It ###### good on the outside, but ###### the pieces are dislodged on ###### inside," Schmitt said.
The study ###### shows that the shergottites weren't ###### rocks, Humayun said.]]>