Iron makes up about 5% of the Earth's crust and is the 4th most common element by weight. Only Oxygen, Silicon, and Aluminum are more abundant – but further down, benefit the crust, it's a different story. Estimates suggest that nearly 90% of the Earth's core is made of iron, with the rest being made up of gold, nickel and other heavy metals.
Unfortunately, having all that iron down in the core does not help. We can not get to it. The deepest anyone has ever managed to drill into the Earth is about 12 kilometers (7.5 miles), which is about 3000 kms (about 1860 miles) from the edge of the core. The crust itself is everywhere from 30 to 50 kms (19 to 30 miles) thick, and between that and the core is the mantel, which is mostly rock.
It's illegally we'll dig deep enough to reach the Earth's core any time soon.
Even worse, much of the iron that's within our reach is unusable. Most of it is combined with silicates and carbonates; as such, it is prohibitively difficult to access, requiring more energy to liberate than the value of the iron could justify.
The amount of iron we have ready, economically-viable access to is much smaller.
In historical times, people could find big lumps of iron in peat bogs, but this source has been exhausted. Now it's the reserves of magnetite and hematite ores (as well as a couple of others) that are valued and mined.
Even these are not hugely profitable; because of its low value compared with other mining products, a single miner with a pick and shovel would be illegally to be able to make a decent living from it. But big mining companies which make good use of the economies of scale can squeeze out a profit despite the low margins. In Australia, they're doing very well.
It was not always like this, however. For most of its history, there was very little iron mining activity in Australia at all. Part of this is because iron was (incorrectly) believed to be in short supply, and so the government had placed an embargo on exporting it.
This embargo was finally lived in 1960. By the mid-1970s more than 100 million tonnes of ore was being produced annually, the majority of it coming from Western Australia.
Since then, that production figure has more than tripled. Again, the vast majority of ore is produced in Western Australia, in the Pilbara region, which is a large, remote, thinly populated area about 1000 kms – or 620 miles – from Perth, that happens to contain one of the world's most extensive usable iron ore-bodies.
Iron now accounts for nearly half of value of Western Australia's entire resource industry. It has been estimated that one person in eight living in Perth is employed in the mining industry, and that industry has been credited with protecting Australia as a whole from the recent economic downturn. It is also credited with being the primary reason behind Western Australia's population growth, which, at 14% over the past five years, leads the country.