The stormy weather is clearing for Rio Tinto plc, BHP Billiton plc and Anglo American plc

I've been pretty bullish in my outlook for a recovering mining sector for a while now, and the modest signs of recovery in prices of some commodities like iron ore have given me some support. But copper has been slipping back of late, so am I wrong in thinking that things are looking better, and have we just been seeing a brief respite with worse to come?

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My Foolish colleague Prabhat Sakya certainly seems to think so, pointing out that the slump in mining shares has come after a 17-year boom for the industry, fuelled almost single-handedly by the rise and rise of the Chinese economy and all the materials needed for its expansion in construction and infrastructure.

He's certainly right about the slowing Chinese demand and resulting over-supply, which has left big miners with debts and spurred a few years of serious cost-cutting. So should I be following the Foolish ethos of carefully examining all opinions (especially contrarian ones) rather than just sticking to my own? Yes!

A good 15 years

Rio Tinto(LSE: RIO) has seen its share price lose 52% over the past five years, to 1,965p as I write. But the shares are actually still up 67%, against a FTSE 100 that has gained just 3% during one of its worst ever periods -- and Rio has also paid decent dividends.

At BHP Billiton(LSE: BLT) there's been an even better long-term result, with shares up 145% over the period to 810p, even after their 63% fall in the past five years. Again, that's with with decent amounts of cash handed out as dividends too.

Anglo American(LSE: AAL) hasn't provided the same long-term rewards for its shareholders, with shares actually down 55% over 15 years, to 575p, and down 80% over the past five years. But Anglo has faced its own well-documented problems in some African operations, and its poorer performance is surely not just a reflection of the current commodities cycle.

So it really could just be a very long cycle we're seeing, and we might have further downside correction to come.

But I'm still reasonably optimistic in the medium-to-long term for these reasons. Firstly, I don't see the wheels having come off the Chinese juggernaut, just perhaps a puncture or two along the way. Chinese growth has overheated, and there are property and banking problems just like we've had in the West (although more opaque, due to an even worse lack of clarity than among our own banks). We might be in for a few years of lower growth from China, but it's a nation of more than a billion hard-working, ambitious people, and they won't be stopped by the occasional setback.

There's more than China

I think it's a mistake to focus solely on China. Last year, China accounted for 20% of Anglo-American's turnover, although that figure was a lot higher at 42% for Rio Tinto and 37% for BHP Billiton. That's a significant portion, and it will likely fall this year and next.

Waiting in the wings we have India, the rest of the developing Asian countries, growing economies in South America, and ultimately Africa (where, as it happens, China is helping lead development in order to secure more raw materials for itself).

I do think Prabhat could be right about the rocky ride continuing, and we might not be at the lowest point yet. But longer term, I still think the pessimism is overdone. 2016 could turn out to be the year we should have bought back into mining shares.

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Alan Oscroft has no position in any shares mentioned. The Motley Fool UK has recommended Rio Tinto. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.