SummaryA prototype petrologic database (MinChem) has been under continual development for several years. MinChem contains petrologic, mineralogical, and bulk-rock geochemical data for Hanford Site sediments collected over multiple decades. The database is in relational form and consists of a series of related tables modeled after the Hanford Environmental Information System (HEIS) structures (BHI 2002). The HEIS-compatible tables were created in anticipation of eventual migration into HEIS, or some future form of HEIS (e.g., HEIS-GEO).