A1 Minerals Ltd (ASX: AAM) disclosed today it had lifted its resource inventory at the big Brightstar gold project in the Laverton district of WA's eastern goldfields by 70%.

This has come as a maiden resource on the Delta prospect on one of the central leases in the Brightstar tenements that are scattered on a north-south line over a distance of 150 kilometres.

Delta has an inferred-indicated resource of 725,000 oz, taking the total Brightstar inventory to 1.7 million oz.

A1 Minerals' managing director, John Williams, said the Delta resource covers a strike of 3.2 km and occurs in several gold domains.

Delta's initial resource is based on a cut-off grade of 0.5 grams/tonne for mineralisation above 100 metres and 1 g/t for material below that depth.

A1 Minerals already has its own CIP treatment plant which it now plans to site at Delta where there is existing mining infrastructure. The property is only 35 km north of the town of Laverton.

Williams said metallurgical testing to date and production data from previous regional operations show the ore to be free milling and can be extracted by conventional CIP processing.

Testwork has determined gold recoveries are similar across the different deposits for both fresh (oxide) and transitional material and average greater than 95%.

A1's plan is to begin producing later this year at a recovered rate of 30,000 oz per annum and has indicated cash costs to be around $US420/oz.

Australian investors, -- reeling from the hard knocks and at times killer blows for exploration and mining in virtually every sector bar gold -- have been taking a more keen interest in juniors with advancing gold resources.

Shares in A1 Minerals closed today at A15 cents, up 3¢ on yesterday.