Lithium Australia NL (LIT) has made application for eight exploration licences in Western Australia in five project locations having a total area of 589 km2. The project areas have been selected on the basis that they either overlie neglected historically reported graphite occurrences or contain other specific geological or geophysical characteristics that signify prospectivity for the discovery of graphite mineralisation. All are greenfield projects, and as such, have seen little in the way of graphite focused exploration. All tenements currently await grant and are 100% controlled by LIT.
Yalbra (Gascoyne, 280 km east of Carnarvon)
The Yalbra Project is located some 5 km along strike from the Buxton Resources Limited (Buxton) JORC compliant Inferred Mineral Resource of 4.0 million tonnes @ 16.2% TGC1 (total graphitic carbon). The deposit was reported by Buxton to be the highest grade JORC graphite resource in Australia. The LIT ground overlies 20 km of the high grade metamorphic unit, the Warrigal Gneiss which is host to most of the graphite elsewhere at Yalbra. The unit is an immediate priority for investigation using advanced airborne electromagnetic (EM) methods.
Donnelly River (Southwest WA, near Manjimup)
At the Donnelly River Project three ELA’s (exploration licence applications) are located over prospective high grade gneiss in an area where graphite mining dates back to 1904. Public domain EM surveys partially cover the tenements and indicate strong conductive responses within the LIT ground. These positive signatures may well represent graphitic horizons at depth and as such present as drill ready targets.
Northern Gully (40 km northeast of Geraldton)
The Northern Gully project is located in an area that has a long history of lead mining with lesser amounts of copper, zinc and silver exploited form around 1850. The Lady Sampson Lead mine lies within the application and exploration in 1972 reported graphite as a common accessory mineral in strained quartz reefs and brecciated pegmatites in areas adjacent to the mine. This occurrence was neglected with the focus being set solely on base metals. LIT believes Northern Gully is prospective for graphite discovery based on the favorable geological environmental and historic recorded graphite occurrences.
Osmond Range (northwest Kimberley)
The Osmond Range project covers a series of electromagnetic (EM) targets within Ahern Formation and Helicopter Siltstone. There are no known graphite occurrences within the tenure and the closest occurrence is the Mabel Downs prospect some 25 km to the west. Public domain EM surveys show a strong east-west conductor possibly related to graphite. The strong EM signatures bear some resemblance to the characteristic responses of the well-known McIntosh deposits to the southwest although the geological characteristics of the areas are different. Nevertheless, the EM targets indicate conductivity at depth and warrant further exploration.
Greenhills (South West Terrane of the Yilgarn Craton, 25 km east of York)
The applications cover metamorphic rocks containing a number of historic graphite occurrences known as the Greenhills Graphitic Zone. A graphitic zone in the Greenhills area extends for up to 20 km in an east-northeasterly direction from Greenhills railway siding towards Doodenanning. Historic sampling of graphite occurrences provided encouraging carbon results and LIT is of the opinion that the area is worthy of further exploration.
The Yalbra application, E09/2172 is located in the Proterozoic Gascoyne Region, and is centered some 280 km east of the coastal township of Carnarvon. It has an area of 249 km². Access is by way of the Carnarvon-Mullewa Road and then internally by station tracks.
Rationale Behind Application
The application is prospective for high grade graphite deposits hosted by the metamorphic rocks of the Warrigal Gneiss. This same unit is the host to Buxton Resources Limited JORC compliant Inferred Mineral Resource of 4.0 million tonnes @ 16.2 % TGC2 (total graphitic carbon) located some 5 km east of the application E09/2172, Figure 1. The deposit was reported by Buxton to be the highest grade JORC graphite resource in Australia.
Buxton have released metallurgical studies reporting commercial grades of flake graphite concentrate containing 91% C(t) with 30% in the medium and coarse categories.3
E09/2172 was applied for to cover prospective ground to the west of the Buxton ground, that contains some 30 km of strike of the Warrigal Gneiss. The Yalbra graphite occurrences are clearly outlined using airborne electromagnetic techniques (VTEM) images, published by Buxton, which appear to strike favorably into the ground applied for by LIT.
High grade metamorphic rocks are a common host to graphite deposits. The east-west trending Errabiddy Shear Zone which separates the Archaean Yilgarn Shield and the Proterozoic Gascoyne Province contains the Warrigal Gneiss which occurs at the western end of the shear zone and contains the major graphitic lenses in the area. Other graphitic units have been described from the Proterozoic gneisses of the Glenburg Terrane to the north.
At Yalbra individual graphitic horizons are traceable for up to 500m and are tens of metres thick. They strike just north of east and are parallel to the regional gneissosity and, on a larger scale, to the Errabiddy Shear Zone. Intersections of over 30% TGC have been recorded in drilling intersections.
The known graphitic zones at Yalbra are clearly distinguishable on the VTEM image shown above in Figure 2, which forms part of the survey which was flown by Buxton in late 2012. It is relevant that the survey did not extend over the ground to the west, which Buxton held at the time as E09/2022 and which was subsequently dropped and is now controlled by LIT.
ELA E09/2172 covers some 30 km of strike to the west and southwest of the presently known Yalbra graphite occurrences and resource. Graphite, being a conductor offers a strong response to electromagnetic survey tools and the Yalbra deposits provide positive signatures. Initial exploration would consist of undertaking geophysical surveys over the prospective Warrigal Gneiss to delineate conductors for drill testing.
The three Donnelly River ELAs E70/4823, 4824 and 4825 are located in the far southwest of Western Australia, immediately to the north and northwest of the regional town of Manjimup. The South West Highway, a major transport corridor, passes through E70/4825 and internal access is provided by secondary roads and forestry tracks. In total the applications cover an area of 174 km².
Rationale Behind Application
The Donnelly River area has a long history of small scale graphite mining dating back to 1904. All applications overlie favorable host lithology being gneisses of predominantly sedimentary origin. Public domain geophysical surveys clearly show a number of conductive units within E70/4823 and E70/4824 which may represent graphitic horizons. These present “walk up” drill targets.
The Donnelly River Deposit is in an area of high-grade metamorphic rocks, formerly known as the Balingup Gneiss Complex, in the extreme southwest corner of the Archean South West Terrane, Figure 3. The metamorphic rocks mostly consist of metasedimentary rocks comprising interlayered quartzite, quartz–mica schist, banded quartz–feldspar–biotite–garnet gneiss, and banded iron formations, together with minor quartzofeldspathic gneiss, amphibolite, calcsilicate gneiss, and ultramafic rock. In addition, about 30% of this area is orthogneiss largely derived from deformed porphyritic granite.
Graphite was exploited from two locations at various times between 1904 and 1943. Donnelly River, originally known as Graphite Hill, from which most production has occurred, is within a 120m wide schist zone in meta-sedimentary gneisses. Only minor production is known from Donnelly River Southeast, which is within schists. Ellis (1953)5 reported that the mineralisation is within a feldspathic clayey graphitic schist with the graphite present as fine amorphous particles.
The Donnelly River Mining Aare was explored in 1984–86 by O’Brien and Giacci Bros Pty Ltd who undertook programs of costeans and RC drilling6. Five graphite lodes were identified, with the principal graphite body having a strike length of more than 100 m with a true thickness varying from 6 to 11 m. Lode samples yielded a carbon content ranging from 25 to 30% TC; however, it was thought that the overall grade would be closer to 20% carbon. Based on a minimum depth of 10 m, it was estimated that about 9000m3 of ore could be extracted from the Lower Lode orebody with the potential to yield about 2000m3 of high-grade, fine-grained (amorphous) graphite after processing.
Cable Sands (WA) Pty Ltd7 explored the area from 1986-88 carrying out a ground EM survey which identified additional conductors. They estimated an exploration target (non JORC) of between 100,000 and 200,000t of ore at 20% TC.
The TEM image in Figure 4, shows the area of the existing public domain surveys in relation to the applications. Of significance are well defined conductive zones within ELA 70/4823 and ELA 70/4824. The general strike of conductors is southwesterly towards ELA 70/4824 Very little of the area covered by the ELAs has been flown.
First pass exploration will be aimed at assembling a digital dataset of all work carried out in the immediate area of the tenements. The ultimate aim would be to extend VTEM geophysical coverage to all three application areas. Existing geophysical targets present immediate drill opportunities.
Northern Gully ELA E66/0095 is situated in the Northampton area in the mid-west of Western Australia some 40 km northeast of the major regional hub of Geraldton. The tenement has an area of 48 km².
Rationale Behind Application
The ELA is located in a Meso-Proterozoic Northampton Inlier largely composed of granulite facies paragneisses, Figure 5. This geological setting is host to graphite deposits elsewhere in WA and locally numerous occurrences of graphite have been noted, especially associated with shear zones in garnet gneisses8. Within ELA E66/0095 a single graphite occurrence, Northern Gully, was noted by Simpson but accurate location of the occurrence has not been verified.
The area has a long history of lead mining with lesser amounts of copper zinc and silver exploited form around 1850. The Lady Sampson Lead mine was evaluated by the Tin Creek Mining Corporation Ltd (Tin Creek) in 19729. Tin Creek reported graphite as a common accessory mineral in strained quartz reefs and brecciated pegmatites in areas adjacent to the mine.
The Northampton Inlier comprises Meso-Proterozoic high grade metamorphic terrane. The inlier is north trending and more than 160 km long, extending between Geraldton to north of Ajana. Locally the area is overprinted by pervasive, northeast regional shearing.
Northern Gully Graphite Occurrence
Simpson reports that “Graphite has been found in … gneisses six miles to the north of the railway … in the usual type of highly ferruginous outcrop rock, which is thickly impregnated with fine flake graphite, interleaved with limonite and mica. Two analyses yielded 16.5 and 19.4% TGC.”
Tin Creek did not assay for carbon but described the graphite occurrences as being largely concentrated in an area south of the Lady Sampson shaft along a ridgeline. Strained pegmatites in the area contain matts of graphite and silicate fillings. Induced polarisation surveys were thought to be influenced by the presence of graphite in the granulites.
There is no known geophysics useful for graphite exploration over the area.
The Northern Gully occurrence has seen no modern exploration despite having been noted in base metal exploration programs. The accurate location and extent of the graphite mineralisation should be located and mapped and reconnaissance mapping undertaken to provide more detail on the prospectivity of the area. Depending on the outcome of this preliminary work decisions will be taken on areas to survey using airborne EM techniques.
The Osmond Range Graphite Project ELA E80/5002 is located in the far northwestern Kimberley Region of Western Australia. The western boundary of the application is some 15 km east of the settlement of Warman (Turkey Creek) on the Great Northern Highway. It has an area of 62 km2.
Rationale Behind Application
The application covers a series of electromagnetic targets within Ahern Formation and Helicopter Siltstone, Figure 6. There are no known graphite occurrences within the tenure and the closest occurrence is the Mabel Downs prospect some 25 km to the west.
ELA E80/5002 is located over Paleoproterozoic rocks lying immediately northeast of the Lamboo Province. The Lamboo Province consists in part of the high grade Tickalara Metamorphics which are host to the McIntosh graphite deposits currently being developed by Hexagon Limited (formerly Lamboo Resources). Hexagon has reported a JORC resource estimate for McIntosh of 17.2Mt @ 4.63% TGC for 797,200 tonnes of contained graphite10. It is described by Hexagon as “the largest JORC compliant flake graphite resource in Australia.”
Locally the application is dominated by rocks of the Ahern Formation, the Helicopter Siltstone and the Duerdin Group. These are, in the main, a sequence of sandstones, conglomerates, mudstones, greywacke and dolomitic sandstones.
Public domain EM surveys show a strong east-west conductor possibly related to graphite, whilst the arcuate conductors to the north are likely related to river beds, Figure 7.
The strong EM signatures bear some resemblance to the characteristic responses of the McIntosh deposits although geologically the areas are dissimilar. Nevertheless, the EM targets indicate conductivity at depth and warrant further exploration. First pass exploration would involve reconnaissance mapping and sampling along with a re-interpretation of available EM data. Sufficient encouragement from this work would promote a decision to drill test anomalies.
The Greenhills Project consists of two applications E70/4811 and E70/4812 having a combined area of 56 km2. They are located between 20 and 30 km east of the town of York and accessed by major roads.
Rationale Behind Application
The applications cover metamorphic rocks containing a number of historic graphite occurrences which have not been subject to evaluation by advanced exploration techniques. Known as the Greenhills Graphitic Zone the prospective units extend for up to 20 km in an east-northeasterly direction from Greenhills railway siding towards Doodenanning.
LIT is of the opinion that these historic occurrences are sufficiently prospective to warrant further investigation.
The applications are located within the South West Terrane of the Yilgarn Craton which is partly composed of a number of highly deformed, Archean gneissic complexes comprising metasedimentary rocks, quartzo-feldspathic gneiss, amphibolite, calc-silicate gneiss, and ultramafic rock. These rocks have been mostly metamorphosed to amphibolite facies with local granulite assemblages of orthogneiss and paragneiss.
A graphitic zone in the Greenhills area extends for up to 20 km in an east-northeasterly direction from Greenhills railway siding towards Doodenanning, Figure 8. In this zone, areas of completely kaolinized, slightly foliated, pale-grey rock contain fine to medium-grained flake graphite crystals interleaved with mica and limonite. Tests revealed the material contained 8.7% TC and approximately 10% of the flake graphite exceeded 0.6 mm in diameter.
At the Doodenanning graphite occurrence Simpson collected two different types of graphitic rock. One specimen contained 5.6% of fine, scaly graphite distributed through a white kaolinite rock. The second sample consisted of a coarser flake graphite (18.7% TC) contained in a highly kaolinized, iron-stained, foliated rock.
There is no known geophysics potentially useful for graphite exploration.
There are no references to graphite focused exploration with the area of the applications. Initial programs should aim to map and survey the original reported occurrences of graphite mineralisation. Samples would then be collected from surface or shallow trenches and submitted for analysis and preliminary metallurgical analysis to determine the potential for marketable quality graphite. If these programs provide sufficiently encouraging results the Company would commission EM surveys to generate targets for drill testing.
Fetherston, J, Michael, 2015, Graphite in Western Australia, Mineral Resources Bulletin 26, GSWA Simpson, E., S., S., Minerals of Western Australia, 1951. Hesperian Press