RESOLUTION OF OXYGEN-ATOMS IN STAUROLITE BY 3-DIMENSIONAL TRANSMISSION ELECTRON-MICROSCOPY

WITH advances in microscope design, high-resolution electron microscopy has become routine, and resolutions of less than 2 Å have been obtained for many inorganic crystals1-4. The images provide a representation of the Coulomb potential (essentially the electron density), but interpretation generally requires comparing experimental images with calculations5. Because the images are two-dimensional representations of the full three-dimensional structure, information is invariably lost. In particular, oxygen atoms are normally not seen. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins6-8. Here we use this technique to obtain a three-dimensional reconstruction of the crystal structure of staurolite, a silicate mineral. We are able to identify the positions of oxygen atoms in the lattice. These results show the potential of the method for high-resolution structure determination on samples that are too small for the use of X-ray techniques. © 1990 Nature Publishing Group.