Granite pegmatite. Grafton field. Located on Isinglass Mountain. First commercial mica quarry in U.S. (1803). Mined for feldspar beginning in 1912, and later for beryl as well. Collecting possible after paying fee ($20 per adult in 2006).
The earliest discovery of the famous gummite specimens from this locality was announced by Benjamin Shaub in 1936: "Recent work in mining for feldspar at the Ruggles' pegmatite has exposed numerous uranium-bearing ... minerals." The very first specimens were apparently collected by Ray and Alvin Schortmann who lived not far from Ben Shaub in Northampton, MA (B. Shaub, pers. comm., 1989). The abundance of gummite was one of the factors which influenced the Schortmann brothers to start a mineral business, beginning about 1938, that lasted for about 25 years.
References:
Sterrett, D. (1914). Some deposits of Mica in the United States (USGS Bulletin 580-F), pp. 80-81.
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: 876, 914, 986.
Morrill, P. (1960), New Hampshire Mines and Mineral Localities.
Gregory, G. (1971), The Ruggles Feldspar - Mica Mine, Grafton, New Hampshire (Rocks & Minerals 46:12-15)
Korzeb, Stanley L.; Foord, Eugene E. and Lichte, Frederick E. (1997):The chemical evolution and paragenesis of uranium minerals from the Ruggles and Palermo granitic pegmatites, New Hampshire (Canadian Mineralogist 35:135-144).
