The most important features of these deposits is that they act like distillation columns for metals. Due to weathering and associated sulfuric acid, different metals separate out at different layers of the geology. This creates valuable concentrations for mining purposes.
In modern mining, we kind of ignore these structures for iron mining purposes even though they are frequently > 50% iron by mass. If you find such a thing, you are more interested in the gold, silver, copper potential that is capped by an iron-rich gossan mineral. Iron is a cost sensitive commodity, you need to be able to mine it at very high concentrations and scales to be profitable. If that mineral has a pile of gold, silver, etc distilled underneath it, you’ll be more interested in that.
Not all copper comes from these mineral formations but a lot is. Often, the hematite is mixed in with the copper mineral. I have a mineral exploration prospect right now which is essentially this. Amazing hematite crystals mixed with copper with strong assay signs of gold underneath. It is a predictable motif in mineral exploration.