Printer Friendly

Meteors and MASS NMR: it's a hit!

A bit of stishovite found at a site where scientists are trying to prove that an asteroid once smacked into the earth would do wonders for their case. The silica mineral has been found in nature only where meteors have hit and created a large impulse of pressure. But testing for stishovite has not been an easy process. The mineral typically comes in such small quantities that it must be concentrated with chemical techniques that often destroy the crystals. And when X-ray diffraction is done on the sample, the stishovite signal is easily obscured by other elements.

In an upcoming issue of METEORITICS, John F. McHone and co-workers at the University of Illinois in Urbana discuss another technique for hunting stishovite: magic-angle sample-spinning nuclear magnetic resonance (MASS NMR), in which the NMR device, normally used in the study of liquids, is "fooled" into treating a spinning sample of ground-up solid material as a liquid. With this method, the researchers clearly detected stishovite in a sandstone rock from a crater in Arizona. "We were able to take a rock right off the ground, grind up, stick it in the NMR and voila! Out came a spectrum," says McHone.

Unfortunately, the technique cannot be used with magnetic minerals, which are common in meteorites and are also found in the clays of the Cretaceous-Tertiary (K/T) boundary that has attracted so much debate over whether an asteroid caused mass extinctions 85 million years ago (SN: 6/2/79, p. 356). McHone, however, believes that this problem may be solved in the near future. He also says that no stishovite was detected in a K/T sample, but it may have been destroyed by the present preparation method.
COPYRIGHT 1985 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1985, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:magic-angle sample-spinning nuclear magnetic resonance
Publication:Science News
Date:Mar 30, 1985
Previous Article:Climate clues glued to rocks.
Next Article:Mapping gaps in environmental data.

Related Articles
NMR patent: a matter of infringement.
Seeing the cell and letting it live.
Blood change linked to cancer.
'Magic angle' reveals zeolite reactions.
Magnetic whispers; chemistry and medicine finally tune into controversial molecular chatter.
Probing chemical signatures in an earthy way.
Marshfield's West keeps nerves in check as he prepares for a spin at state meet.
Winterstein rallies North.
On the rise: Brian Letendre making magic in Broadway's Mary Poppins, even while sitting still.

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters