Barian magnetoplumbite from Mangruvan, Örebro, Sweden

Abstract

Barian magnetoplumbite occurs as rare, microscopic grains (generally ≤0.1 mm) in locally remobilized braunite‐silicate ore from the Mangruvan manganese‐iron deposit. The average composition, derived from electron‐microprobe analyses, is Pb_0.69Ba_0.33(Fe_7.58Mn²⁺ _1.28Mn³⁺ _1.75 Ti_1.17Sb_0.06Zn_0.05Al_0.10)O₁₉. The mineral displays chemical zoning where Pb varies inversely with Ba; Pb ranges from 0.61 to 0.89 atoms pfu. It is intimately associated with jacobsite [Mn²⁺ _0.95Zn_0.03Mg_0.02(Fe_1.56Mn³⁺ _0.44) O₄], pyrophanite [Mn_0.98Ba_0.01(Ti_0.90Sb_0.06Fe_0.05)O₃] and hematite [Fe_1.93 Ti_0.03Mn_0.04O₃]. Of the major elements constituting the magnetoplumbite, Pb, Fe, and Mn were derived from the local, primary assemblage, whereas Ba, and possibly Ti, was supplied hydrothermally from a more distant source.

Stridsberg, S. & Turek, V., 1997: A revision of the Silurian nautiloid genus Ophioceras Barrande. GFF, Vol. 119 (Pt. 1, March), pp. 21–36. Stockholm. ISSN 1103–5897.

Keywords:

• Magnetoplumbite
• hexagonal ferrite
• Långban type
• Mangruvan (Nyberget)
• Sweden