The mining sector has been shown to be a popular safe haven for investors worried about the fallout from the Brexit vote. Indeed, Rio Tinto (LSE: RIO) has surged 10% since last week’s vote.

On paper this seems a wise strategy, the global nature of commodities demand making the industry’s major players less immune to the economic travails facing one or two regions.

But this doesn’t mean the world’s diggers have no problems of their own, with many raw materials markets struggling under vast amounts of unwanted material and demand indicators still struggling.

Latest manufacturing PMI data from China overnight comes as a particular concern. The official gauge for June slipped to 50 from 50.1 the previous month. And the unofficial Caixan release was even worse, a reading of 48.6 slipping from 49.2 times in May and illustrating further contraction.

Until supply/demand data begins to improve, I believe the likes of Rio Tinto are unattractive stock picks, particularly as a predicted 34% earnings slide for 2016 creates a slightly-heady P/E rating of 17.4 times.

On the rise

Financial giant RSA Insurance Group (LSE: RSA) has recovered strongly following an initial dip last Friday, and the stock is now dealing at levels not seen since September. And I believe further hefty gains could be in the offing.

The company announced today that it had successfully shed its assets in Uruguay, a move than completely removes its exposure to Latin America. RSA has already withdrawn from Brazil, Argentina, Chile and Colombia in recent months.

These moves significantly reduce its global exposure, and in particular remove the possibility of surging long-term returns from lucrative emerging regions. Still, the measures are working wonders in slashing costs. And I reckon RSA’s decision to double-down on its core markets of the UK, Scandinavia and Canada should still deliver resplendent returns.

Investors should be mindful of RSA’s dependence on Britain, its home market and responsible for more than 40% of net written premiums. But I believe a P/E rating of 13.5 times is fair price given the insurer’s exciting growth plans.

Money flows

Oil driller Gulf Keystone Petroleum (LSE: GKP) has also benefitted from the charge to commodity stocks in recent days. Meanwhile, the firm has been boosted by updates surrounding its Shaikan oil field.

Today the energy play announced that cumulative output from its asset in Northern Iraq has reached 25m barrels. Consequently Gulf Keystone now owes a $10m bonus payment to the Kurdistan Regional Government (KRG).

The business is now negotiating a deal with authorities regarding the payment, it advised. Earlier this week Gulf Keystone advised in two separate statements it had received $8m and $7m from the local government as payment for May’s exports, with the balance “expected to be paid shortly.”

The energy giant has been in a long-running battle with KRG officials over such payments, a situation that look set to run and run. On top of this, Gulf Keystone also has questions to answer over the strength of its balance sheet, not to mention the long-term outlook for oil prices.

And with the fossil fuel play expected to remain lossmaking until 2017 at the earliest, I reckon risk-averse stock pickers should steer well clear.

Follow this Foolish advice

But whether or not you share my bearish take on Gulf Keystone Petroleum, I strongly recommend you check out this special Fool report that could help you become a market millionaire.

Our 10 Steps To Making A Million In The Market report highlights how fast-growth small-caps and beaten-down bargains are all fertile candidates to produce tenfold returns.

Click here to enjoy this exclusive wealth report.  It's 100% free and can be sent straight to your inbox.

Royston Wild 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.