Fluorite Question and Confesion

[valen1014]

I think I did something bad...

I set up a 2.5 gallon with fluorite (no fishes) and decided that besides adding root tabs I would dust some iron (II) sulfate heptahydrate below the fluorite . It's hard to tell how my plants are doing because I took these plants from a tank in which they were already dying (I planted them in sand but I think they started rotting because I never stirred the sand and so there were a LOT of air gaps in it). I was just trying to rescue the plants really...

The fluorite, which was black the first few days, now has patches of golden/brown/rust color... the drawf sags I planted also seem to have a lot of the rust color around them where their roots start to go into the fluorite. Have you guys seen this with fluorite before? I guess I should suspect it is the iron?