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Bostwickite, a new calcium manganese silicate hydrate from Franklin, New Jersey

Published online by Cambridge University Press:  05 July 2018

Pete J. Dunn
Affiliation:
Department of Mineral Sciences, Smithsonian Institution, Washington DC 20560, USA
Peter B. Leavens
Affiliation:
Department of Geology, University of Delaware, Newark, Delaware 19711, USA

Abstract

Bostwickite, CaMn63+Si3O16-7H2O, is a new species from the Franklin Mine, Franklin, New Jersey. Chemical analysis yielded MgO 0.9, CaO 5.1, Mn2O3 56.3, Fe2O3 0.5, Al2O3 1.0, As2O5 1.0, SiO2 20.1, H2O [15.1], sum = 100.0%. This yields (Ca0.76Mg0.19)Σ0.95(Mn5.973+Fe0.053+)Σ6.02(Si2.80Al0.16As0.075+)Σ6.02(Si2.80Al0.16AS5+0.07)Σ3.03O16·7.01H2O, corresponding to the idealized formula. The strongest lines in the X-ray powder diffraction pattern are (d, I): 11.3, 100; 3.548, 30; 2.898, 30; 2.567, 40; 2.262, 25; 2.238, 25; 1.470, 25. Bostwickite is dark red in colour; hardness c. 1 (Mohs'); density (meas.)= 2.93 g/cm3. It occurs in radial aggregates of acicular compound crystals. Optically, bostwickite is biaxial negative with 2Vα = 25deg; α = 1.775, Β = 1.798, γ = 1.800;, dispersion strong, r > v; strongly pleochroic with α = β redbrown, γ = yellow-brown; absorption is α = β = γ. Bostwickite is named in honour of Richard C. Bostwick, collector and compiler of data on the minerals of Franklin and Sterling Hill.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1984

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References

Dunn, P. J. (1979) Mineral. Record, 10, 160–5.Google Scholar
Frondel, C. (1972) The minerals of Franklin and Sterling Hill; a check list, p. 43. John Wiley & Sons, New York.Google Scholar
Palache, C. (1935) The minerals of Franklin and Sterling Hill, Sussex County, New Jersey. U.S. Geol. Surv. Prof. Paper, 180, 122.Google Scholar