Transmission Electron Microscopy of Terrestrial Rocks and Minerals

Abstract

Comprehensive application of transmission electron microscopy (TEM) to rocks and minerals has been made possible by the recent introduction of reliable ion beam thinning devices. The potential of TEM as a diagnostic tool for evaluation of the thermal history, mode of formation, age and general environment of both terrestrial and lunar materials is a matter of considerable present interest. Studies of terrestrial basalts and volcanic glasses at this University have recently revealed that TEM can provide information of considerable diagnostic significance, a specific example of which is given below.Figure 1 is a view of twin bands which we have commonly observed in the plagioclase (Labradorite) component of an olivine basalt from the Cascade Mountains, Oregon. The twin planes are defined by parallel light and dark contrast fringes, and selected area diffraction indicates that we are observing albite twins with composition plane (010). Of particular interest is the morphology of the albite twins at region A. For purposes of comparison, Fiqure 2 reproduces the characteristic appearance of a growing annealing twin in the metal nickel.