Abstract
Ammonium feldspar was grown hydrothermally from a gel, having a stöchiometric Al2O3·6SiO2 composition. As a source for NH +4 , a 25 percent NH3 solution was used. Internal Cr/CrN and graphite/methane buffers fixed the fugacity of NH3 during the experiments. Unit cell parameters of the synthetic ammonium feldspar are a: 0.8824 (5) nm, b: 1.3077 (8) nm, c: 0.7186 (4) nm, β: 116.068 (12)°, V: 0.7448 (34) nm3. the X-ray power diffraction pattern is measured and indexed in accordance to the space group C2/m. Infrared and thermal gravimetric analyses provide no evidence for the presence of structurally bound water molecules in the crystal structure of synthetic ammonium feldspar. Hydrothermally grown anhydrous ammonium feldspar is shown to be identical to the mineral buddingtonite by the similarity of the data between the synthetic and natural materials. There may be justification for considering natural buddingtonite as an anhydrous feldspar with the ideal formula NH4Si3O8. Reexamination of natural specimens is desirable.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Barker DS (1964) Ammonium in alkali feldspars. Am Mineral 49:851–858
Beran A (1986) A model for the allocation of water in alkali feldspars, observed from infrared spectroscopy investigations. Phys Chem Minerals 13:306–310
Erd RC, White DE, Fahey JJ, Lee DE (1964) Buddingtonite, an ammonium feldspar with zeolitic water. Am Mineral 49:831–857
Gulbrandsen RA (1974) Buddingtonite, ammonium feldspar in the Phosphoria Formation, Southeastern Idaho. J Res US Geol Survey, Vol. 2, nr. 6:693–697
Hallam M, Eugster HP (1976) Ammonium silicate stability relations. Contrib Mineral Petrol 57:227–244
Hamilton DL, Henderson CMB (1968) The preparation of silicate compositions by a gelling method. Mineral Mag 36:832–838
Higashi S (1982) Tobelite, a new ammonium dioctahedral mica. Mineral J 11:138–146
Hofmeister AM, Rossman GR (1985) A spectroscopic study of irradiation coloring of amazonite: structurally hydrous, Pb bearing feldspar. Am Mineral 70:794–804
Hori H, Nagashima K, Yamada M, Miyawaki R, Marubashi T (1986) Ammonioleucite, a new mineral from Tatarazawa, Fujioka, Japan. Am Mineral 71:1022–1027
Kimball MR, Megaw HD (1974) Interim report on the crystal structure of buddingtonite. In: MacKenzie WS, Zussman J (eds) Feldspars. Proc. NATO ASI on Feldspars, Manchester. Manchester Press, pp 81–86
Kimbara K, Nishimura T (1982) Buddingtonite from the Tōshichi Spa, Iwate Prefecture, Japan. Kobutsugaki Zasshi, J Mineral Soc Jpn 15:207–216 (In Japanese, with English Abstract)
Loughnan FC, Roberts FI, Lindner AW (1983) Buddingtonite (NH4-feldspar) in the Condor Oilshale Deposit, Queensland, Australia. Mineral Mag 47:327–334
Ribbe PH (1963) A refinement of the crystal structure of sanidinized orthoclase. Acta Crystallogr 16:426–427
Shigorova TA, Kotov NV, Kotel'nikova YeN, Shmakin BM, Frank-Kamenetzkiy VA (1981) Synthesis, diffractometry and IR-spectroscopy of micas in the series from muscovite to the ammonium analogue. Geochem Int 18:76–82
Strom C (1976a) UNITCELLC, An interactive APL program for computing cell constants. Geol Mineral Institute, State University of Leiden, The Netherlands
Strom C (1976b) Indexing crystal faces on SEM photographs. J Appl Crystallogr 9:291–297
Tuttle OF (1949) Two pressure vessels for silicate-water studies. Geol Soc Am Bull 60:1727–1729
Voncken JHL, Wevers JMAR, Van der Eerden AMJ, Bos A, Jansen JBH (1987) Hydrothermal synthesis of tobelite, NH4Al2Si3A1010(OH)2, from various starting materials and implications for its occurrence in nature. Geol Mijnbouw 66:259–269
Woensdregt CF (1982) Crystal morphology of monoclinic potassium feldspars. Z Kristallogr 161:15–33
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Voncken, J.H.L., Konings, R.J.M., Jansen, J.B.H. et al. Hydrothermally grown buddingtonite, an anhydrous ammonium feldspar (NH4AlSi3O8). Phys Chem Minerals 15, 323–328 (1988). https://doi.org/10.1007/BF00311036
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00311036