1. Dep. of Earth and Planetary Sciences; Univ. of Tennessee; Knoxville TN 37996
2. Chemical and Engineering Materials Division; Oak Ridge National Lab.; Oak Ridge TN 37831
3. Dep. of Geosciences; Texas Tech Univ.; Lubbock TX 79409
4. Environmental Sciences Division; Oak Ridge National Lab.; Oak Ridge TN 37831
5. Physical Measurement Lab.; National Institute of Standards and Technology; Gaithersburg MD 20899