9628453 Sack This grant provides $31,081 as one-half support of the costs of upgrading Purdue University's Earth and Atmospheric Science Department's current Cameca SX-50 electron microprobe (EMP) with a new computer and software for both automated mechanical control of the instrument and subsequent X-ray image analysis and a new vacuum evaporator used for chemical preparation of samples to be analyzed. Specifically, the upgrade will include a Sun SPARC 20 workstation and Cameca's SX-pack software package which includes both mechanical control software and software for X-ray image analysis and interpretation. The new computer equipment will replace an antiquated PDP-11/53 minicomputer that was supplied with the EMP when it was purchased with support from NSF in 1972. Software support for the PDP-11 computer is no longer available through Cameca. Their present vacuum carbon coater, also purchased in 1972, experiences mechanical failures frequently and will also be replaced. This upgrade will allow this lab to continue their highly regarded research program in mineral thermodynamics and crystallography using a vintage but clearly still useful EMP as the analytical centerpiece for major elemental analysis of geological samples. The upgraded SX-50 will also serve a broader community of both institutional and regional users. ***