Mining the ore isn't the problem. Extraction is. Gold is native gold, so easy to seperate. Iron requires clever furnaces and processing to produce, and it's not until recently we could make mild steel consistently.
On a more-than-proof-of-concept scale, you have https://www.youtube.com/watch?v=RuCnZClWwpQ, a traditional blacksmith family in Burkina Faso mining a few kilograms of iron with several person-days of work, which is probably about 1000× as productive as the Primitive Technology guy achieved (perhaps a gram of iron after about a person-day of work). But the US steel industry employs 87000 people to produce about 120 million tonnes of iron and steel per year, which works out to about 5000 kg of iron and steel per person-day. (And that's why Burkina Faso imports its iron instead of smelting it in the way demonstrated in that documentary, the way they had done for the previous 2500 years, until some French guys wrecked a Jeep there in the early 20th century.)
So there are something like six or seven orders of magnitude over which "high-tech" machinery can increase your iron productivity, or, to look at it another way, over which the price of iron can vary even once you have the know-how.
