Amber Worth 13, of Park Avenue, was killed after a half-tonne boulder fell on her in Carlton Main Brickworks in Grimethorpe last April.

A jury at Sheffield Coroner’s Court heard that the boundary failed to meet regulations for keeping out trespassers because the fencing and signposts were stolen as quickly as they were replaced.

Chartered mining engineer John Carlon, who had carried out inspections of works at the quarry since 1999, said he believed a wire mesh fence topped with barbed wire would have been enough to meet the regulations.

Amber, a pupil at Willowgarth High School, had been playing with friends for 15 to 20 minutes before the 3ft-wide block of sandstone fell on her.

She died instantly.

Det Sgt Paul Brook, who investigated the death, told the hearing Amber appeared to have slipped down the face of the crevice and dislodged the boulder.

He said: “Her friends tried to move it but they didn’t have a chance.”

At the time of her death, teachers said Amber was a star pupil who was destined to be head girl.

The hearing was told Amber was a convivial, effervescent, adventurous and popular young woman.

Her friends described her as a truly beautiful girl.

The inquest was adjourned until a later date.