Drilling aimed at testing pegmatites across St George’s Mt Alexander project in WA has struck proverbial gold with the intersection of a wide, continuous pegmatite interval at the Manta target.

Diamond hole MAD213, which tested the Manta seismic reflector, intersected a 121m continuous pegmatite interval from a depth of 631.2m though various additional intervals of varying widths intersected from 369m to 624m took the total pegmatites up to 225m.

When this thick pegmatite is combined with the size of the Manta reflector, which is modelled as a saucer shape with a diameter of about 1,000m, it is clear that St George Mining (ASX:SGQ) could be on to something very exciting at Mt Alexander.

Little wonder then that the company is planning to carry out further drilling at this target albeit at a shallower depth to initially test where the pegmatite is interpreted to intersect, or underly, the outcropping greenstone sequence.

The granite/greenstone interface is considered more prospective for pegmatite hosted mineralisation compared with the granite intrusion which may be the source of the pegmatite.

“This is an exciting development in our lithium exploration at Mt Alexander,” executive chairman John Prineas said.

“The early results from MAD213 are very encouraging with a large intersection of pegmatite that may be associated with significant structural activity.

“We are looking forward to further drill testing this very large pegmatite unit.”

Manta seismic reflector

Manta was first modelled late last year as a seismic reflector occurring within a granite intrusion immediately north of the outcropping greenstone belt at Mt Alexander.

The company’s initial interpretation suggested that the reflector could be a structurally emplaced portion of the greenstone belt to the south and therefore a viable target for nickel sulphides, similar to the high-grade nickel-copper-PGE mineralisation intersected at the Cathedrals Belt, ~3km north of Manta.

However, the drilling of MAD213 and subsequent geophysical testing of the core has shown the prominent reflector is probably associated with an interval containing numerous pegmatites below the granite, including one interval of 120.8m thickness.

Pegmatite intervals from Manta are now being sampled for assaying to determine if there is any anomalous mineral or geochemical composition.

Manta pegmatites also appear to differ from the numerous outcropping cross-cutting pegmatites within the interpreted Mt Alexander lithium-caesium-tantalum corridor in that they may have been intruded into a relatively flat extensional structure over a wide area.

Lithium drilling

Current reverse circulation drilling at Mt Alexander is designed to test a wide area of the 15km pegmatite corridor where numerous steep dipping, cross cutting pegmatites have been identified in outcrop.

These include the lithium mineralised pegmatites at the Jailbreak about 9km south of Manta.

Additionally, this corridor is adjacent to the Copperfield Granite, interpreted to be one source of the mineralised pegmatites at Mt Alexander and at Red Dirt Metals’ Mt Ida lithium project about 15km south of Jailbreak.

The Mt Ida fault is also associated with Liontown Resources’ giant Kathleen Valley lithium deposit about 100km to the north.




This article was developed in collaboration with St George Mining, a Stockhead advertiser at the time of publishing.


This article does not constitute financial product advice. You should consider obtaining independent advice before making any financial decisions.