The aircore program returned assays such as 54m at 758 parts per million total rare earth oxide from surface, including 9m at 1129ppm TREO from 23m, and 43m at 877ppm from 8m.
Of the 22 holes drilled, 20 encountered mineralisation and all contained zones of higher-grade REEs exceeding 1000ppm, with peaks of 3607ppm.
The breakdown of specific rare earths was described as highly variable, with heavy REEs representing between 8-90% and light REEs between 10-92%.
The drilling was limited to an area spanning 500m by 500m.
Fourteen holes ended mineralisation, and the target is open in all directions.
Managing director Mike Dunbar said the Hyden target, named for a nearby town, was surprising given the shallow nature of the clays, with little or no surficial cover, and the width and consistency of the mineralisation.
The area has seen limited previous work for REEs, with most past exploration focused on gold, nickel and graphite.
Licograph had returned up to 46,716ppm TREO in the clays for which there are a few possible explanations.
Since it is unlikely Hyden hosts the highest grade clay system globally, the graphite may have locally upgraded the mineralisation, or there is a possible hard rock pegmatite or a carbonatite source in the area.
Mamba has since kicked off 50 holes targeting a bedrock gravity anomaly, 2.5km east of the maiden drilling that was completed in January.
The early success provides more support to the idea there is bedrock mineralisation in the area.
Mamba optioned the Hyden REE project in November for A$25,000 from private vendor Licograph in November, and can trigger the option for $1 million.
With surrounding ground pegged under its own right, Mamba has around 1300sq.km in the area.
Mamba started the year with $2.2 million cash.
Shares in Mamba were up 87% this morning at 14c, capitalising it at $8.5 million.
It has traded at 7-25c over the past year.
