1977/03/01 by I. S. Oen, E. A. J. Burke, C. Kieft
paper · doi:10.1180/minmag.1977.041.317.12
crossref issued 1977/03/01 · crossref published 1977/03/01 · crossref published-print 1977/03/01 · crossref created 2006/12/15 · crossref published-online 2018/07/05 · crossref deposited 2021/02/05 · crossref indexed 2026/07/30
Summary Microprobe and X-ray investigation of a mineral occurring with breithauptite, nickeline, and other arsenides in the naujaite at Igdlúnguaq, Ilímaussaq alkaline massif, S. Greenland, shows that this mineral, which was formerly misidentified as ‘maucherite’, is a westerveldite (Fe 0·85 Ni 0·15 )As, of much iron-richer composition than the nickeloan westerveldites from the only two other known occurrences of this mineral. Westerveldite from Igdlúnguaq was presumably formed by reaction of nickeline with iron-rich solutions under conditions of reheating at temperatures of about 450° C and under partial pressures of arsenic below those necessary to stabilize nickeline. Sulphur-bearing löllingite occurs as exsolution blades in the westerveldite. Iron-rich nickeline, up to a composition (Ni 0·82 Fe 0·18 )As 0·95 Sb 0·05 , was presumably formed by recrystallization of nickeline in the transition stage just before this mineral became unstable and was replaced by westerveldite.