Can tech firms ensure they never buy conflict minerals?

Four years ago President Obama signed a piece of legislation called the Dodd-Frank Act. Most of it had to do with the tighter regulation of the financial sector. But tucked away at the back of the Act - section 1502 - was something completely different. An attempt to eliminate - or at least limit - the use of so-called "conflict minerals" - things like gold, tungsten, tin and tantalum - in the manufacture of consumer electronics.

Many such minerals come from Africa...from the Democratic Republic of Congo. Under the terms of the act, US listed companies will need to demonstrate to the Securities and Exchange Commission that they have exercised "due diligence" in trying to ensure minerals they use have not been sold to the benefit of armed groups.

There's nothing to actually STOP a company USING conflict minerals - but any company wanting to label its products "conflict-free" will have to undergo an independent audit.

Computer chip maker Intel is one firm which says it's already doing everything required by Dodd-Frank. The company's Carolyn Duran says she and her team have spent the last five years checking the provenance of the minerals they use.