Composing a granite plug nearly 1 kilometre in diameter and some 250 metres in depth, the tantalum-rich deposit was surveyed by Canadian firm Watts, Griffis & McQuatt in the late 1970s. Geological data from the region has only recently been collated by the Saudi Geological Survey. The new study is expected to be completed in February 2003 and a decision on production will be made by the end of 2004.

Tantalum is a dense metal used in a variety of electronic components. The price of the metal has risen sharply over the last decade in response to growing demand for PCs and mobile phones.

'The scale of production depends on how much you can sell into the market, not how much you get out of the ground,' says Patrick Cheetham, executive chairman of Tertiary. 'The telecoms market has been depressed and large inventories have built up recently, but we predict strong demand at about the same time we have to make a production decision.'