Green’s Dictionary of Slang

1. cocaine.

1931		Irwin Amer. Tramp and Und. Sl. 87: Gold Dust. — Cocaine, so called from its value and from the happiness and comfort, however fleeting, which it gives to its devotees.
1949		Monteleone Criminal Sl. (rev. edn).
1959		J.E. Schmidt Narcotics Lingo and Lore.
1969		R.R. Lingeman Drugs from A to Z (1970).
1971		E.E. Landy Underground Dict. (1972).
1987		Eble Campus Sl. Spring.
2001		ONDCP Street Terms 10: Gold dust — Cocaine.

2. heroin [+ ref. to the colour of, presumably, the Chinese (brown) variety of heroin].

1975

G. Underwood ‘Razorback Sl.’ in AS L:1/2 59: gold dust n Heroin.