The Mineral Deposit Inventory (MDI) provides information on metallic, non-metallic, industrial and building stone occurrences/deposits across Ontario.

Each MDI record provides all or some of the following information: deposit name(s), location, status (e.g., occurrence, prospect, producer, past producer), commodities, character/classification, geological structure, lithology, minerals and mineral alteration, geochemistry, exploration history, and production and reserve data where available. Also included are notes on deposit visits and references to additional publications related to the deposit.

This database is an updated inventory of mineral deposits in the province of Ontario and supersedes previous Mineral Deposits Inventory (MDI) releases. Originally compiled in the early 1970s by the Resident Geologist Program (RGP), the database is continually being reviewed and updated by RGP staff. There are approximately 150 new records and 850 updated records in the 2013 release.

MDI data are provided in 2 formats in this release: 1) a relational database, and 2) MDI provincial coverage in a geospatial GIS (ESRI® shape file, point and polygon) format. The complete MDI relational database is provided in Microsoft® Access® 2003 format. For the geospatial data, basic mineral deposit information (MDI number, commodities and property status) is provided. Geospatial data are provided in North American Datum 1983 (NAD83) geographic co-ordinate system using Geodetic Reference System 1980 (GRS80).