Maine, USA

Deposits of rare-element-bearing and gem-bearing granite pegmatites are well-known in Oxford, Androscoggin, and Sagadahoc Counties in the southwest portion of the State. These pegmatites were formerly noted for ceramic-grade feldspar production along with beryl and sheet muscovite. There are many lithium- and cesium-enriched LCT pegmatites in the Oxford County and Androsoggin County Field. In Sagadahoc County, Li- or Cs-enriched LCT granite pegmatites are uncommon and there are some NYF pegmatites, present. Additional granite pegmatites occur in Cumberland County and scattered in other areas. Additional deposits include small generally low-grade lead-zinc-copper sulfide deposits along the coastal region with a few important sulfide deposits in the eastern part of the coastal region and several larger high-grade deposits in the north central part of the state ranging from Oxford, Franklin, Somerset, Piscataquis, and Aroostook Counties. Large low-grade manganese silicate deposits are present in Aroostook County. Granite quarries are widespread in the southern portion of the State including coastal regions. High grade slate is still quarried in the Monson District. Lime-grade marble is still quarried in the Thomaston District. Much of the State is composed of metamorphic and plutonic igneous rocks, with relatively few sedimentary rocks.

References:
- King, V. and Foord, E., 1994, Mineralogy of Maine, Volume 1.
- King, V. and Foord, E., 2000, Mineralogy of Maine, Volume 2.

New detailed Mineralogy of Oxford County, Maine in progress. First Volume will be Maine Feldspar, Families, and Feuds appearing in May 2009.