Diamond drilling on the Indonesian island returned 57m at 3.83 grams per tonne gold equivalent, including 32m at 5.76gpt gold equivalent and 20m at 7.4gpt gold equivalent, and 58m at 2.71gpt gold equivalent, including 13.7m at 4.47gpt gold equivalent and 6.3m at 1.69% copper.
Both intersections were from surface.
The gold zone is underlain by a thick pile of base metal mineralised breccias rich in lead-zinc, returning 54m at 2.75% copper-lead-zinc from 49m.
Robust described the widths and grades of the intersections as potentially economic and believes Batu Mas could host world-class gold mineralisation.
Mineralisation at the prospect, part of the Lakuwahi project, remains open in all directions.
Robust is preparing a maiden resource estimate for the project.
Late last month, the company signed an air charter agreement with SUSI Air for charter services between Kupang and Kisar to enable more regular transport of drill core samples, personnel and supplies.
Shares in Robust jumped 5.7% or A10c to $1.85.