Buddingtonite

Buddingtonite
General
CategorySilicate mineral
Formula
(repeating unit)		NH4AlSi3O8
IMA symbolBud[1]
Strunz classification9.FA.30
Crystal systemMonoclinic
Crystal classPrismatic (2)
or sphenoidal (2/m)
Space groupC2/m (no. 12)
Unit cella = 8.57 Å, b = 13.03 Å,
c = 7.18 Å; β = 112.73°; Z = 4
Identification
ColorColorless
Crystal habitCompact masses replacing plagioclase as pseudomorphs
CleavageGood on {001}, distinct on {010}
TenacityBrittle
Mohs scale hardness5.5
LusterVitreous
StreakLight grey to yellow (impure specimens)
DiaphaneityTransparent to translucent
Specific gravity2.32
Optical propertiesBiaxial (+)
Refractive indexnα = 1.530 nβ = 1.531 nγ = 1.534
Birefringenceδ = 0.004
2V angleCalculated: 60°
References[2][3][4][5]

Buddingtonite is an ammonium feldspar with formula: NH4AlSi3O8 (note: some sources add 0.5H2O to the formula). It forms by hydrothermal alteration of primary feldspar minerals. It is an indicator of possible gold and silver deposits, as they can become concentrated by hydrothermal processes. It crystallizes in the monoclinic crystal system and is colorless to white with a vitreous luster. Its structure is analogous to that of high sanidine (KAlSi3O8). Buddingtonite has a hardness of 5.5 and a specific gravity of 2.32.

Buddingtonite was discovered in 1964 at the Sulfur Bank mine near Clear Lake in Lake County, California.[6] Clear Lake is at the north end of The Geysers geothermal area. It also occurs in the Tonopah, Nevada[7] area and in hydrothermal areas in New Zealand[8] and Japan. It has also been reported from the sedimentary Phosphoria Formation in Idaho,[9] South Dakota,[10] Wyoming, and Montana. It occurs in the oil shale deposit, near Proserpine, Queensland, Australia.[11]

It was named for Arthur Francis Buddington (1890–1980), a petrologist at Princeton University.

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (2005). "Buddingtonite" (PDF). Handbook of Mineralogy. Mineral Data Publishing. Retrieved 14 March 2022.
  3. ^ Buddingtonite, Mindat.org, retrieved 13 June 2022
  4. ^ Webmineral data
  5. ^ Mookherjee, M.; Redfern, S. A. T.; Swainson, I.; Harlov, D. E. (December 2004). "Low-temperature behaviour of ammonium ion in buddingtonite [N(D/H)4AlSi3O8] from neutron powder diffraction". Physics and Chemistry of Minerals. 31 (9): 643–649. Bibcode:2004PCM....31..643M. doi:10.1007/s00269-004-0425-8. hdl:2027.42/46909. S2CID 47007808.
  6. ^ Erd RC, White DE, Fahey JJ, Lee DE (1964). "Buddingtonite, an ammonium feldspar with zeolitic water". American Mineralogist. 49 (7–8): 831–50.
  7. ^ Felzer B, Hauff P, Goetz AFH (1994). "Quantitative reflectance spectroscopy of buddingtonite from the Cuprite mining district, Nevada". Journal of Geophysical Research. 99 (B2): 2887–95. Bibcode:1994JGR....99.2887F. doi:10.1029/93JB02975.
  8. ^ Yang K, Browne PRL, Huntington JF, Walshe JL (2001). "Characterizing the hydrothermal alteration of the Broadlands-Ohaaki geothermal system, New Zealand, using short-wave infrared spectroscopy". Journal of Volcanology and Geothermal Research. 106 (1–2): 53–65. Bibcode:2001JVGR..106...53Y. doi:10.1016/S0377-0273(00)00264-X.
  9. ^ Gulbrandsen RA (1974). "Buddingtonite, ammonium feldspar, in the Phosphoria Formation, southeastern Idaho". USGS Journal of Research. 2 (6): 693–7.
  10. ^ Solomon GC, Rossman GR (1988). "NH4+ in pegmatitic feldspars from the southern Black Hills, South Dakota". American Mineralogist. 73: 818–21.
  11. ^ Loughan FC, Roberts FI, Linder AW (1983). "Buddingtonite (NH4-feldspar) in the Condor Oilshale Deposit, Queensland, Australia". Mineralogical Magazine. 47 (344): 327–34. Bibcode:1983MinM...47..327L. doi:10.1180/minmag.1983.047.344.07. S2CID 140724010.