The intercept also included 7m at 12.7g/t; while another highlight was 46m at 4.76g/t gold from 50.2m.
Ongoing drilling results have now extended the depth of the target from 80m in February to 155m.
"Based on the current dataset, it appears there is a northern plunge which is similar to other major deposits in the surrounding area," president and CEO Nana Sangmuah said.
Mankouke South is about 25km east of B2Gold's Fekola mine in western Mali.
Roscan said this mineralised system was structurally aligned with Mankouke South mineralisation, which occurred in the structural corridor that also hosted Iamgold's Siribaya deposits to the south, Roscan's Mankouke Central prospect and Oklo Resources to the north.
The company, which changed name from Roscan Minerals in 2018, said exploration had not been impacted by COVID-19 to date.
It appointed former AngloGold Ashanti president Sir Samuel Jonah as non-executive chairman in January.
Roscan was one of the four finalists at Mining Indaba's Investment Battlefield in February.
It said last month it was set to receive C$2.6 million from the exercise of warrants at 12c per share, and planned to use the proceeds for exploration in west Mali.
Roscan shares have spent much of the past year below the 20c mark and hit a multi-year high intraday of 38c.
They closed up 40.4% to close at 36.5c, capitalising it about $70 million (US$50 million).
