Maine Mineral Resources Data System

Data Sources

The Maine Mineral Resources Data System is derived from three separate databases:

• Data records/location coordinates - shapefile for Maine downloaded from the U.S. Geological Survey's MRDS website.
• Data records/location coordinates - shapefile created from the "Maine Metallic Mineral Deposits Database" (created for the Maine Geological Survey by F. M. Beck, Inc. in 1999).
• Location coordinates - shapefile created for the following publication: Thompson, W. B., Wintringham, N. A., and King, V. T., 2000, Maine mineral locality index, in King, V. T. (editor), Mineralogy of Maine; Volume 2: Mining history, gems, and geology: Maine Geological Survey, p. 355-426.

Data Modifications

The three data sources listed above were combined and modified as follows:

• Database Content

  Sand and gravel operations are not included in the Maine Mineral Resources System database. All sand and gravel operations were deleted from the USGS MRDS database at the start of the project.

• Location Coordinates

  All coordinates for the original data were projected to WGS84. Corrections to location coordinates were determined as follows: Coordinates with the highest degree of confidence were contained in Thompson and others (2000) and Beck (1999). USGS MRDS locations were corrected to use coordinates from Thompson where possible, coordinates from Beck if Thompson did not exist, and the original USGS coordinates if neither of the previous were available. Other locations were corrected using original source materials where MRDS coordinates did not match the town/county location listed in the database.

• Duplicate Records

  Duplicate records were identified and deleted using comparison of locality name, synonym, geographic proximity, commodity listings, and reference to original source material when necessary.

• Consolidation of Database Fields

  Fields from Beck (1999) were correlated with USGS MRDS fields and renamed with common field names.

• Merging of Records

  The USGS MRDS data was merged with the Thompson and F.M. Beck databases to create the final master database. Data for localities with multiple records were combined into a single record using the record with the most accurate coordinates.

• Additional Database Fields

  Town, county, and quadrangle fields were added. Fields for record source, record comment, location source, and location comment were added.

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Last updated on April 15, 2009

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