# Mining Iron

**URL:** <https://boards.straightdope.com/t/mining-iron/542659>\
**Category:** Factual Questions\
**Created:** [June 10, 2010, 2:58pm UTC](https://boards.straightdope.com/t/mining-iron/542659 "2010-06-10T14:58:35Z")\
**Posts on this page:** 1\
**Page:** 2

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**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\
**Post date:** [June 11, 2010, 1:39am UTC](https://boards.straightdope.com/t/mining-iron/542659/21 "2010-06-11T01:39:22Z")

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> [@Sage\_Rat](#):
>
> Hm, the Wikipedia page on [bloomeries](http://en.wikipedia.org/wiki/Bloomery) seems to be saying that fluxing wasn’t necessary, so the need for limestone wouldn’t be there.
> 
> But so if red soil isn’t a particular indication of the presence of an iron vein, how do they usually find one? Usually, there is somewhere where you can actually see the vein from the surface?

Wiki has it right. Fluxing isn’t _necessary_ but it increases the yield of iron you get from a particular batch of iron ore. If you don’t add a flux, the part-reduced iron ore FeO will react with silica impurities in the ore to produce liquid fayalite slag that drains to the bottom of the hearth. That cleans the iron produced but leaves some of your iron bound up in the slag.

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