[Arcaeca]

So I got some steel wool and burnt it - not for the makeshift sparkler, but to make iron(III) oxide, only to find out that that reaction actually makes (supposedly) iron(II) oxide. However, iron(II) oxide is black, but much of my burnt steel wool has a blue tinge, almost as vibrant in Prussian blue in certain spots despite no discernible source of cyanide ions. Does anyone know what compound the blue is and if/how it can be isolated from the rest of the iron metal and iron(II) oxide?

[AWK]

Not every color comes from a colorful substance, sometimes from a subtle surface structure. In the photo, you can see the crystal of iron oxide Fe₃O₄.
https://i.pinimg.com/originals/ee/29/33/ee29336a195262199653ad3fa2da8916.jpg