Australia's youngest billionaire Nathan Tinkler goes bust...

• Australia's youngest billionaire Nathan Tinkler goes bust
• Tinkler rode Australian coal boom driving by Asian demand
• Private jets, horses, sports teams all gone

(Adds quotes, details)

Rags-to-riches coal mining baron Nathan Tinkler, who rode the mining boom to become Australia's youngest billionaire before losing it all when coal prices collapsed, has been declared legally bankrupt after failing to pay off a private jet.

The bankruptcy order comes 10 years after the 40-year-old former mining electrician scraped together a A$1 million ($728,700) deposit for a rundown coal mine that returned a profit of A$442 million 18 months later.

At that time, coal was at the forefront of a boom in Australian mining, with rising orders from fast-industrialising Asia creating a rush of development and consolidation.

Tinkler parlayed a series of audacious deals into a fortune, far removed from his days as an apprentice at one of BHP's coal mines, where he is said to have spent much of his free time scouring share prices in newspapers.

He toyed with the idea of going to university, but, as he later told BRW magazine, he felt he would "fail uni (university) the same way I did high school I was just not cut out for hitting the books," according to a biography written by Australian business writer Paddy Manning.

By 2012, the resources boom and Tinkler's fortune had begun to unravel, with at least three of his stable of some 50 firms facing hundreds of millions of dollars in lawsuits.

As coal prices plummeted, Tinkler was forced to sell an array of assets, including a beloved thoroughbred horse stud as well as professional soccer and rugby league clubs based in gritty coal shipping town of Newcastle.

"To be honest, there aren't that many assets to chase anymore," John Melluish, Tinkler's bankruptcy trustee told Reuters. "There's not a lot there."

After splashing out big on sports cars, race horses and homes in Hawaii, it was Tinkler's failure to come up with $2.25 million owed on a Dassault Falcon 900C private jet that tipped him over the edge.

At one stage Tinkler was reported to be losing more than A$4 million a day on paper as coal prices tanked and shares in his big stake in Whitehaven Coal (WHC) plummeted.

A subsequent attempt to take Whitehaven private flopped and he eventually had to hand over his Whitehaven stake to creditors including Credit Suisse and hedge fund Farallon Capital.

In December, Tinkler told Reuters he believed he could make a comeback in coal, and said environmental opposition, as much as low coal prices were hurting his chances.

"I've shown I can make money from coal once, and I hope I can do it again," he said.

In October last year, Tinkler emerged as chief executive of Australian Pacific Coal (AQC) , which has agreed to acquire the majority of a coal mine from Anglo American AAL.L . He was forced to step down four months later under Australian regulations barring bankrupt individuals from holding corporate directorships.

The bankruptcy order had been stayed for 21 days. ($1 = 1.3723 Australian dollars)