This data release provides a vector digital dataset developed from the published metamorphic map of Massachusetts. This data release is a digital representation of the metamorphic map shown on sheet 2 of the bedrock geologic map of Zen and others (1983). The original publication from 1983 was available in paper only. A scanned raster version of the 1983 map was obtained from the National Geologic Map Database catalog and converted to the geologic map schema known as GeMS. The original metamorphic map was published at 1:500,000-scale. The data release contains GIS files and a metadata file for the database and for each feature class. The GIS files include CartographicLines and ContactsAndFaults as lines, MapUnits and OverlayPolys as polygons. The metamorphic map units range from greenschist to granulite facies. Boundaries between map units include contacts, metamorphic facies boundaries, and faults. References: Zen, E-an, Goldsmith, Richard, Ratcliffe, N.M., Robinson, Peter, Stanley, R.S., Hatch, N.L., Shride, A.F., Weed, E.G.A., and Wones, D.R., 1983, Bedrock geologic map of Massachusetts, U.S. Geological Survey, 1:250,000,3 sheets, sheet 2 - Metamorphic Map, scale 1:500,000, https://ngmdb.usgs.gov/Prodesc/proddesc_16357.htm.