Phosphovanadylite; a new vanadium phosphate mineral with a zeolite-type structure

• Published in: The American mineralogist 1998-08, Vol.83 (7-8), p.889-895
• Main Authors: Medrano, Marjorie D, Evans, Jr, Wenk, Hans-Rudolf, Piper, David Z
• Format: Article
• Language: English
• Subjects: Caribou County Idaho; crystal chemistry; crystal structure; electron probe data; Enoch Valley Mine; formula; Idaho; lattice parameters; metals; mineralization; Mineralogy; Minerals; new minerals; nonsilicates; Paleozoic; Permian; phosphate deposits; phosphates; Phosphoria Formation; phosphovanadylite; Soda Springs Idaho; unit cell; United States; Vanadium; Zeolites
• ISSN: 0003-004X; 1945-3027
• DOI: 10.2138/am-1998-7-821

Phosphovanadylite, whose simplified formula is (Ba,Ca,K,Na), [(V,Al)4P2 (O,OH)16] · 12H2O, is a new vanadium phosphate zeolite mineral found in the Phosphoria Formation at Monsanto's Enoch Valley Mine, Soda Springs, Idaho. Its formula in more detail is (Ba0.38 Ca0.20 K0.06 Na0.02)Σ0.66 [P2(V3.44 A10.46)Σ3.90 O10.34(OH)5.66] · 12H2O). The drusy mineral occurs as pale greenish-blue euhedral cubes (20-50) µm edge) coating phosphatic, organic-rich mudstone. The chemical composition determined by electron microprobe is (in weight percent) V-28.02, P-9.91, A1-1.97, Ca-1.31, Ba-8.28, Cd-0.09, Zn-0.34, Na-0.15, K-0.73, O-46.57, and F-0.03. The index of refraction is nD = 1.566 (4) and specific gravity is 2.16 (3). The X-ray powder pattern shows strong reflections at 3.16 Å (422), 2.58 (600), 2.44 (620), and 7.73 (200), which are indexed on the basis of a cubic body-centered unit cell with a = 15.470 (4) Å. From the single-crystal structure analysis, its space group was determined to be I4̄3m, Z = 6, and its structure consists of V4O16 octahedral clusters linked to each other by P atoms to form a cubic lattice, creating cavities 7.0 and 5.5 Å in diameter where mainly H2O resides. Final residual indexes are R = 0.066, Rw = 0.061, goodness-of-fit = 0.75, and 93 observations and 24 parameters.