Abstract
Johnbaumite was found as a vein-forming mineral in crystalline limestone near gehlenite-spurrite skarns at Fuka, Okayama Prefecture. It is associated with arsenopyrite, löllingite, garnet, magnetite and calcite. Wet chemical analyses and EPMA of the mineral yield an empirical formula (Ca4.961Fe0.005) Σ4.97(As2.991P0.024) Σ3.02 O12(OH0.651F0.278Cl0.071) Σ1.00 on the basis of (O, OH, F, Cl) = 13. The DTA and TG curves, and IR spectrum are measured, and the optical and X-ray diffraction properties agree with previous data.
Johnbaumite from Fuka may be formed by reaction of As, Fe, S, etc.- bearing fluids with limestone.
