Green’s Dictionary of Slang

new-chum adj.

(Aus./N.Z.) inexpert, inexperienced, raw.

1857		Bell’s Life in Victoria (Melbourne) 30 May 2/5: ‘Why you shall hedge your bets, you new-chum sweep’.
1864		E. Wardley Confessions of Wavering Worthy 171: We threaded our way, with peering and new-chummish curiosity.
1865		Chudleigh Diary 2 Feb. (1950) 165: Turned a swell handle for Dr Wareing a new chum doctor.
1885		Bulletin (Sydney) 28 Feb. 11/1: He was a new-chum cleric, and meeting a bullock team […] he enquired of the gentleman in charge: ‘Aw—you are, what I am told is called a bullock-driver, are you not?’ ‘Jest as y’ like,’ replied the other; ‘but it’s bull-punchers we call ’em here.’.
1899		E.W. Hornung Amateur Cracksman (1992) 65: I must trust to the sound sleeping of Ewbank upstairs [...] knock the visitor down, or shoot him with the revolver I had been new chum enough to buy before leaving Melborne.
1903		J. Furphy Such is Life 93: I was workin’ mates with a raw new-chum feller las’ winter, ringin’ on the Yanko.
1908		C. Tomalin Venturesome Tom 31: WANTED, a good steady, sober NewChum young man, who can drive a quiet horse, milk a cow.
1926		J. Doone Timely Tips For New Australians 9: The word ‘pommy’ is ascribed to the new chum Englishman in Australia.
1933		Townsville Daily Bull. (Qld) 3 June 12/6: The new chum cove laughed.
1957		J. Hawke Follow my Dust! 61: I always like to hear you new chum bastards asking fool questions.
1968		S. Gore Holy Smoke 25: Suppose one of youse had been lumbered with some newchum dimwit who’d let a few of yer woolly jumbucks go bush, eh?

In compounds

new-chum gold (n.) [a newly arrived ‘digger’ might be fooled into thinking he had discovered the real metal]

(Aus.) iron pyrites, ‘fool’s gold’.

1876		Melbourne Punch 28 Dec. 4: [cartoon caption] NEW CHUM GOLD. Young Digger.—‘And why do they call it mica?’ Old Digger (tired of answering questions).—‘After Mike O'Donahoo, who first discovered it. Every fool knows that’.
1912		Australasian (Melbourne) 9 Mar. 46/4: And now we’ll run the rule over this new chum gold [...] They ‘ran the rule’ over the big quartz outcrop, and its metal was iron pyrites.
1927		Townsville Dly Bulletin (Qld) 19 Mar. 11/2: And back through years of solid toil / I see myself, as brave and bold I started forth to delve the soil. / And found my prospect— / new chum gold.
1933		Camperdown Chron. (Vic.) 28 Feb. 7/1: New Chum Gold. There is a mineral called pyrites, of a yellow colour and deceptive appearance, which is well known amongst miners as ‘New Chum Gold’.
1941		Baker Popular Dict. Aus. Sl.
2003		McGill Reed Dict. of N.Z. Sl. 141: new chum’s gold Fool’s gold.