Companies mining for diamonds on an island off the west coast of the Eyre Peninsula are confident of finding kimberlite rock containing more diamonds on the island.
Kalyan Resources and Orogenic Exploration recently had their exploration lease for Flinders Island, 35 kilometres west of Elliston, extended for three years.
Orogenic Exploration director and geologist Steve Cooper said exploration work had taken place on the island for several years and a large number of diamonds had already been recovered.
Mr Cooper said the company was confident there were more diamonds on the island and it was a matter of locating the kimberlite, igneous rock that could house diamonds.
"We're looking for kimberlite but are having trouble pinpointing exactly where, we know it's on the northern part of the island," he said.
"Other minerals we did find are very fragile, don't travel well and can only come out of kimberlite, which holds the diamonds."
Mr Cooper said more geophysical surveys and drilling were planned in accordance with environmental requirements.
He said exploration had also revealed grains of the unusual garnet G10 pyrope on the island, as well as olivine.