As bands within banded sphalerite of carbonate-hosted deposit in Belgium. One of a few mixed/intermediate valence compounds of such deposits, that include subsulphites (seeUnnamed (Fe Subsulphite)), sulphites (compareUnnamed (Fe Sulphite)), pyrosulphites (Unnamed (Fe Pyrosulphite)), sulphoxylanes (seeUnnamed (Fe Sulphoxylane)), thiosulphates (compare'UM1995-34-SO:Fe' andUnnamed (Fe Thiosulphate II)).'UM1995-35-SO:FePb' is also in the list.

These compounds are generally banded/radial/fibrous/spherulitic in form and have lowered reflectivity with growing sulphur valence; they are precursors of the banded sulphide ores.

Sulphite compounds in these deposits are also found as syntaxial intergrowths with disulfides andgoethite.

Compare other sulphites, known as approved minerals:albertiniite,scotlandite,gravegliaite,hannebachite.