A brazen thief who crashed a stolen sewage truck through a fence at a Western Australian gold mine then filled it with gold-bearing liquid from a holding dam is "the dumbest person" in town, the company says.
Kalgoorlie's Gold Stealing Detection Unit is investigating the recent attempted "heist" at Northern Star Resources' Kanowna Belle mine.
"It's the most ridiculous thing I've heard and witnessed in Kalgoorlie," chief executive Stuart Tonkin told AAP at the Diggers and Dealers Mining Forum on Tuesday.
"You've just got to look for the dumbest person in Kalgoorlie and you'll find them."
Mr Tonkin suggested the financial loss was unremarkable as the thief or thieves "don't know what they're doing."
"There's really no value. It's a trespassing issue," he said.
"None of our staff were harmed, that's the key thing."
Asked about mine security, Mr Tonkin said the remote operation could be swathed in barbed wire "and someone can still drive a truck through it".
