Talk:Carbonyl iron

What is Carbonyl Iron?
Carbonyl iron is sold as an iron supplement; but what is its chemical formula? Is the simply elemental iron (Fe) which was produced by some (unknown to me) special catalytic process which used the carbonyl radical? Or is this a salt or compound of iron? FeCO or FECOOH or something? I have seen iron supplement advertised as elemental carbonyl iron -- how could it be both elemental & carbonyl? (I can't for the life of me find out what is the valence of the carbonyl radical!) I hope some editor can thus clarify this article. I have also seen Carbonyl iron or iron carbonyl in Wikipedia furter explained as another name for iron pentacarbonyl, which is also said to be very toxic! (PeacePeace (talk) 21:02, 4 January 2020 (UTC))