The previously Ghana-focused junior this week secured the rights to acquire an 80% interest in two exploration licences in the Pilbara, where prospectors have reportedly found gold nuggets.

The region's conglomerate prospectivity has sparked a gold rush and keen investor interest of late, originally sparked by Novo Resources (CN:NVO) and Artemis Resources (AU:ARV).

Castle acknowledged it was making "an opportunistic transaction" and said its geologists would soon travel to site to determine whether the area met its geological expectations.

It said the licences encompassed the prospective basal conglomerate horizon of the Hardey Formation and its unconformable contact with the underlying Mount Roe Basalt, as mapped by the Geological Survey of Western Australia.

Nickel and cobalt explorer Collerina Cobalt (AU:CLL) made second place after reporting excellent nickel, cobalt and aluminium recoveries from its Homeville deposit in New South Wales.

Meanwhile, Canyon Resources (AU:CAY) was queried by the ASX today in response to its share price jump from A$0.093 last Wednesday to $0.125 today.

In response, Canyon said noted the recent relative strength in the global alumina and bauxite markets, its continuing work with the Cameroon government regarding bauxite opportunities, and the recent underwriting of its unlisted $0.60 option series which is expected to result in about $2.5 million in capital.