Abstract
Sideronatrite Na2Fe(SO4)2(OH)-3H2O was found on marcasite - pyrite - bearing quartz vein from the Tako coast, Kusimoto, Wakayama Prefecture, Japan.
EPMA analyses (WDX mode) leads the empirical formula, (Na1.54, K0.00)1.54(Fe3+1.04, Al0.01)1.05 (SO4)2.02(OH)0.65 - 3.25H2O.