Elevated REE levels have been returned from the large Kalkaroo copper-gold-cobalt deposit and Croziers copper prospect while historical results from Eurinilla and Birksgate prospects also reveal REE.
Two drill samples from West Kalkaroo contain elevated levels of higher value REE, with up to 1,355 ppm neodymium (Nd) and 366 ppm praseodymium (Pr).
Havilah has started studies on the Kalkaroo project to investigate the potential for economic recovery of an REE concentrate as a by-product.
Eleven drill samples from Croziers are similarly elevated in REE, with up to 953 ppm Nd, 425 ppm Pr, 5,443 ppm lanthanum (La) and 6,104 ppm cerium (Ce).
Levels “warrant follow-up”
The company’s technical director Dr Chris Giles said: “The elevated REE levels in fairly typical West Kalkaroo saprolite gold ore drill samples clearly warrant careful follow-up studies.
“The critical questions for Havilah are what mineral(s) host the REE and can the REE be recovered and concentrated to produce a saleable, direct shipping by-product along with copper concentrates?
“We plan to initiate some strategic metallurgical test work to investigate these questions due to the potential opportunity to enhance the Kalkaroo project economics.”
REE are of relevance and strategic importance given the Australian Government’s recent efforts in promoting international investment in the development of critical minerals resources within Australia.
Havilah shares are up 9% today to 12 cents.
Most historic exploration in the Curnamona Craton has been directed at base metal, uranium and gold mineralisation, meaning that REE were not routinely assayed.
Given the strategic importance of REE, Havilah believes that study of REE distribution and grade across its deposits and prospects is warranted due to the potential opportunity to enhance the deposit and/or project economics.
New REE assays are from re-assaying of selected retained drill samples from West Kalkaroo and the Croziers copper prospect. REE assays are also presented for earlier MMG JV drilling at Eurinilla and Birksgate prospects.
West Kalkaroo samples
Two copper-gold mineralised reconnaissance aircore drill hole samples recently re-assayed from West Kalkaroo show elevated levels of higher value REE, namely Nd, Pr, dysprosium (Dy) and terbium (Tb).
These four elements make up around 80% of the potential value of REE in the two samples, which are from the soft clayey saprolite gold ore at West Kalkaroo.
The levels of these REE in the underlying copper ore types is yet to be determined, although previous limited La assay values were generally elevated.
Composites of 11 drill samples also re-assayed from two Havilah reverse circulation holes at Croziers returned elevated REE, although with higher relative proportions of the light-REE, namely La and Ce.
REE analyses reported earlier by MMG Limited from a diamond hole at Croziers compare favourably with Havilah’s new assays.
Higher value REE at Croziers are spatially associated with the copper skarn mineralisation in the fresh and oxidised zones.
It has been possible to broadly outline a REE mineralisation envelope at Croziers in pink and grey. This partially overlaps a copper mineralised envelope (green) and abuts a potential tungsten mineralised zone (yellow).
Giles said: “While the Kalkaroo project will be the initial focus for REE test work, in due course exploration drilling of the stratabound copper-gold mineralisation will also follow-up the associated elevated REE at several other locations in the Curnamona Craton such as Croziers and Eurinilla.”
Exploration drilling planned for the current quarter will primarily target copper and tungsten mineralisation at Croziers but will also be designed to search for extensions of the associated untested REE mineralisation.
The re-assaying was prompted by a recent technical review by Havilah’s new management team of limited REE data available from earlier MMG joint venture diamond drill holes on several Havilah prospects, along with compilation of La and Nd data from a limited number of Havilah drillholes.
MMG reported some elevated REE results from both the Eurinilla and Birksgate prospect areas, generally associated with copper-gold mineralisation.
While the available limited REE results are promising, considerably more exploration drilling and assaying is required to determine the full extent of mineralisation associated with the stratabound replacement and vein style copper-gold mineralisation across Havilah’s Curnamona Craton tenements.
At Kalkaroo, Havilah’s REE program will be in addition to milestone completion of the updated project pre-feasibility study, which is well advanced.
Possible value upside
The value upside for Havilah is that if REE can be economically recovered in a mineral concentrate as a by-product of the standard copper and gold recovery processes it potentially provides a further revenue stream for the Kalkaroo project.
REE have a wide variety of important and often energy saving modern age usages because of their spectrum of slightly varying chemical behaviours.
For example, modern brushless electric motors as used in power tools and many electric vehicles rely on powerful new generation magnets that use Nd, Dy, Pr, Tb compounds as vital components.
Source for the above diagram: China Water Risk report 'Rare Earths: Shades of Grey-Can China continue to fuel our clean and smart future?' (published June 2016).