Green’s Dictionary of Slang

1. of a mine or goldfield, to prove unproductive.

1885		H. Finch-Hatton Advance Aus.! 279: The lode had ‘duffered out’, and [...] it was useless to continue working.
1889		Cassell’s Picturesque Australasia IV 73: Cloncurry has, to use the mining parlance, duffered out.
1897		D. McK. Wright Station Ballads 111: A good bit of ground duffers out [OED].

2. of a miner or prospector, to fail in one’s searches; thus duffering adj.

1889		H. Lawson ‘The Sleeping Beauty’ in Roderick (1967–9) I 60: ’Tis very plain he’d struck it fat, / This dufferin’ London muff.
1890		‘Rolf Boldrewood’ Miner’s Right 58: ‘So you’re duffered out again, Harry!’ she said.