Another friend said Stainton had worked in the mine for more than seven years and knew "every aspect of the place".
He was regarded as a "great guy" as well as being a keen hunter and fisherman.
His long-term partner Hemopo was said to be heartbroken.
Earlier the work family of Stainton paid tribute to him.
Police said Stainton was found dead inside the wreckage after an underground mine rescue team carried out an overnight search for the missing man at OceanGold's Correnso mine.
Mining union, E tū this morning expressed its support and condolences, saying miners were much like a family and the man's death was ''tragic" and ''untimely".
"The mining community is close-knit and in many respects like a family", Mr Myles said.
"There will be grief and shock over what's happened, and we want to ensure people are well-supported", he says.
It was too early to speculate on the cause of Stainton's death but the union was confident Worksafe and the company would investigate thoroughly, Mr Myles said.
At a press conference this morning, mine boss Bernie O'Leary said the loader he was in rolled in a large open area called a stope, which is like an underground cave.
Stainton was putting backfill material into that area.
A 29-year-old man died in an underground loader like this one. Photo / OceanaGold
The incident happened about 6.30pm yesterday.
Her said Waihi was a close community and the mine's thoughts are with the worker's family.
"The task at hand that the operator was performing was the backfilling of waste rock into the void, a void created by mining out gold bearing rock, and during the backfilling operation this is when the accident took place."
Mr O'Leary said it was the first time in the company's 25-year history in New Zealand that a worker had been killed.
Between 25 and 30 staff were working on the shift at the time of the accident.
He said training and the Worksafe practices operated in the mine were extremely high. He says this is a very unfortunate incident.
He said the whole community would be feeling for the family today.
OceanaGold chief executive officer Mick Wilkes last night said the company was co-operating fully with authorities to determine the cause of the accident.
"We are all deeply saddened by this tragic event," said Wilkes.
"On behalf of all employees at OceanaGold I offer our deepest prayers and condolences to the family of the worker and employees of the mine."
Area Commander Inspector John Kelly thanked all those involved in the rescue operation and offered his sympathies to Stainton's family and friends.
