On the sulfides in the sediments of the Bothnian Sea

[摘要] Sediments starting with the Ancylus stage of the Baltic up to the Litorina stage contain considerable amounts of sulfide. Sulfide minerals of six samples were studied microscopically, chemically and by X-rays. Framboidal pyrite spherules occur in the sulfide-rich sediments whereas those with only sparse sulfide are black and contain pigmentous amorphic sulfide incorporated with colloids. Also marcasite-bearing framboidal spherules were verified. The chemical composition of the sulfides and also the size frequency distribution of the framboids are presented with diagrams.