The programme saw 11 holes totalling 2,811m completed.
Highlight intervals were 1.6m (meters) at 353g/t (grams per ton) silver from 185.6m downhole, within a broader interval of 49m at 43g/t silver in one hole.
Buenavista is a precious metal-bearing, structurally controlled vein system in northwest Durango, 270km northwest of Durango city.
The drill rig has been moved to the nearby Bermudez project which is permitted and ready to drill and will be the fifth and final project to be drilled under the terms of a strategic investment by Fortuna, added Prospero.
Bermudez is a low sulphidation epithermal system with multiple kilometres of exposed veining at the surface. An initial program of three holes for a total of 1,500m (meters)of core drilling is planned.
Prospero shares were unchanged at C$0.085.