Mr Railton (51) was found by Ned and Maggie Smith on the Sawpit Gully Trail about 6pm on Wednesday.
Despite calling for help and performing CPR until paramedics arrived, Mr Railton was pronounced dead at the scene.
Yesterday, Grant Railton, of Arrowtown, said his brother's loss would be felt widely in the tight-knit community.
Mark Railton was born in the township, attended Arrowtown School and grew up in Wakatipu.
Grant Railton said his younger brother was a machine operator for Railton Contracting, a family business started by his father, Graeme.
However, he had also done stints in the fishing and gold-mining industries - the latter was his passion.
On Wednesday, he had been walking Sawpit Gully for training ahead of gold-mining this summer.
''He loved walking in the hills and rivers looking for gold.
''He and a mate had a claim on the Buckleburn River.
''From what it sounds like, he pretty much died instantly doing what he loved - hiking in the hills.''
Grant Railton said that initial indications were his brother had suffered a heart attack.
''He was a good guy, he was a genuine guy, he'd do anything to help.''
Mark Railton's funeral will be held at 1.30pm on Monday at the Lake Hayes Pavilion.
