Black Mountain Quarry (Black Mountain pegmatite), Rumford, Oxford Co., Maine, USA
|Latitude & Longitude (WGS84):||44° 35' 7'' North , 70° 38' 47'' West|
|Latitude & Longitude (decimal):||44.58528,-70.64639|
|Köppen climate type:||Dfb : Warm-summer humid continental climate|
Granite pegmatite. Oxford field.
Primarily a mica quarry with four closely spaced nearly overlapping pits. Noted for its mineral specimen variety and for opaque pink toumaline fans in quartz and lepidolite matrix, some of which have been over 50 cm long. No tourmaline pockets have been found at this location to date, although occasional fraudulently labeled transparent rubellite specimens have been strongly promoted as "definitely one-of-a-kind" by their sellers. Locally, these are derisively attributed to "Maine-nibia", "Maine-istan", or "Maine-zil".The eosphorite from this locality was formerly the world record size (37 mm).
Not to be confused with the 'Black Mountain locality' (http://www.mindat.org/loc-6537.html).
Mindat ArticlesWeird Times at Black Mountain Quarry, Rumford, Maine by Douglas Watts
57 valid minerals. 1 (TL) - type locality of valid minerals. 6 erroneous literature entries.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Ludlow - Wenlock|
423 - 433.4 Ma
|Silurian Smalls Falls Formation|
Age: Silurian (423 - 433.4 Ma)
Stratigraphic Name: Smalls Falls Formation
Comments: Named the Penobscot formation for Penobscot Bay, central-south ME. Consists of metamorphosed shaly sediments (slates, schists, quartzites) typically developed along nearly whole length of western shore of Penobscot Bay. Color varies from light gray through steel gray and purplish gray to black, the darker grays being predominant. Locally injected and metamorphosed by granite and diorite. Weathered surfaces usually rusty. In a few places only the rock exhibits a very perfect slaty cleavage, highly inclined to bedding planes. Conformably overlies Battie quartzite. (ME025) Unit description from USGS GEOLEX website (ME078). AA - Low rank amphibolite facies; AB - Medium rank amphibolite facies; AC - High rank amphibolite facies; E - Epidote-amphibolite facies; GS - Greenschist facies; Protolith C - Sulfidic/carbonaceous pelite
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. 
Maillot, E. E., Boos, M. F., and Mosier, M. (1949). Investigation of Black Mountain beryl deposit, Oxford County, Maine: U. S. Bureau of Mines, Report of Investigations 4412.
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 969.
Guidebook 1 to Mineral Collecting in the Maine Pegmatite Belt
Prepared by members of the Maine Federation Club 1973 pg. 22
Rocks & Minerals (1988): 63: 129-130.
Dyar, M.D., Guidotti, C.V., Core, D.P., Wearn, K.M., Wise, M.A., Francis, C.A., Johnson, K., Brady, J.B., Robertson, J.D., and Cross, L.R. (1999) Stable isotope and crystal chemistry of tourmaline across pegmatite-country rocks boundaries at Black Mountain and Mount Mica, southwestern Maine, USA. European Journal of Mineralogy: 11: 281-294.
Moore, P. B., 2000, Analyses of Primary Phosphates from Pegmatites in Maine and Other Localities, in V. T. King (editor), Mineralogy of Maine. Mining History, Gems, and Geology, Maine Geological Survey, Augusta, Maine, p. 333-336.
Wise, Michael A.; Brown, Cathleen D. (2011): Chemical composition of coexisting columbite-group minerals and cassiterite from the Black Mountain pegmatite, Maine. European Journal of Mineralogy 23, 817-828.