President and CEO Warren Rehn said the results were showing an improvement in gold grades on average, compared with previous results.
"This further supports our plan to develop the project and process this high-grade material in our oxide plant at Velardeña," he said.
The company said earlier this month mining operations at Rodeo were possible for the first quarter of 2021, pending the receipt of permits which were submitted in June.
Rodeo has a 2017 indicated resource of 0.4 million tonnes grading 3.3g/t gold and 11g/t silver, for 46,000oz and 200,000oz respectively.
Total preproduction capex was put at US$1.5 million for a nine-quarter operation with an after-tax NPV8 of $22.5 million, according to a preliminary economic assessment released in April.
Golden Minerals also released a PEA for its Velardeña silver-gold project in April, saying the addition of a relatively low-cost bio-oxidation circuit at the existing processing facility helped create an "attractive scenario for a potential restart".
The company had put Velardeña's mines on care and maintenance in 2015 and leased the oxide mill to Hecla Mining until the end of this year.
Golden Minerals raised $8.6 million in an upsized raising in July priced at 42c per share.
Its share price (NYSE American: AUMN) closed up 8.6% to 42.56c yesterday, at the upper end of a one-year range and capitalising it at $63.3 million.