Out on the remote archipelago of Tierra del Fuego in Chile, Toto Gesell holds on to a profession that hails from bygone times: gold prospecting. Every day, come rain or shine, he puts on his rubber boots and heads to a local creek, where he searches for specks of gold the old-fashioned way: with a pan, a shovel and a homemade sluice. His daily routines are documented with great tenderness in Alfredo Pourailly De La Plaza’s absorbing documentary, shot over nearly a decade. The camera often lingers on Toto’s wrinkled hands, as he carefully handles tiny flecks of the precious metal, or writes down his hopes and dreams in a neatly kept diary. Despite his contentment with this simple way of life, his body is etched with the physical toil of the demanding work.

When Jorge, Toto’s worried son, decides to build a trommel from scratch to help automate his father’s work, the film acquires the fervour of a monumental quest. This colossal undertaking ends up taking years; through riveting editing, the documentary oscillates between two competing timelines: one of the trommel’s gradual completion, and another of Toto’s declining health, as the juxtaposition accentuates the urgency of Jorge’s mission. When Toto suffers a serious health crisis while prospecting, the preciousness of time feels as tangible as the gold dust that slips through his fingers.

Occasionally, the film shifts its focus away from these intimate, domestic moments to take in the beauty of the Tierra del Fuego landscape. And in the end, the trommel stands not just for filial piety, but also for the love of a whole community. Rich with meticulous detail, De La Plaza’s documentary also doubles as an act of visual scavenging; among these lush fields of grass and snowcapped mountain peaks, the film-maker has also struck gold.

• The Fabulous Gold Harvesting Machine is on True Story from 26 June.