a reply to: bloodymarvelous
Ochre does not equal iron ore, per se, it is decomposed iron ore with sand or clay mixed in.
It is from 20%-70% limonite(iron oxide) and hematite(also iron oxide).
Up to 60% of that converts to usable iron oxide after pre smelting heating, of which 70% will convert to pig iron.
But pig iron is not a usable form.
Now here is one thing nobody has mentioned, the shear amount of wood required to make iron.
Smelting the ore is not the only use, the ore must be heated to drive out the moisture.
Then wood must be made into charcoal before smelting. Charcoal is obtained at a rate of about 1 to 4 from wood.
But smelting the ore does not produce usable iron, it makes pig iron full of impurities.
The iron must be heated and beaten to force out the impurities.
I seem to remember that it takes 1600lb of wood to make one pound of usable iron.
As harte pointed out iron making leaves a huge footprint in the record when just considering the actual smelting proccess, but its footprint goes
beyond just that.
Somebody has to cut the wood, some one has to haul it, somebody has to make charcoal, somebody has to haul the charcoal, somebody has to mine the
silica rich rock for flux, and crush it and haul it as well.
Then there are the people mining, crushing, cooking and transporting the ochre.
Then there are all the other ancilliary jobs that go along with all those people, like farmers to feed them, potters to make the containers they will
need, husbandrymen to raise the livestock use ti work the fields and haul the needed commodities.
And all of the infrastructure need to service the previous.
Also, any metal smelting operation leaves an undeniable mark on the environment.