The auriferous iron sulfide was finely disseminated through the quartz.
The other important class of strongly magnetic minerals is the iron sulfides, particularly greigite and pyrrhotite.
These iron sulfides were long considered to be pyrite.
The soils on the lake beds are naturally rich in iron sulfides.
The black color is due to the high amounts of iron sulfide generated by the green sulfure reducing bacteria.
In a few species which dwell near hydrothermal vents, iron sulfide is used to construct the shell.
Its is a mixed zinc and iron sulfide.
The gas then passed on to the gasholder and the iron sulfide was sold to extract the sulfur.
Higher carbon content causes greater deposition of iron sulfide, which appears as a black varve.
In a parallel reaction the iron sulfide is converted to slag: