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Eneabba District
Western Australia, WA, Australia
Main commodities: Ti Zr REE

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The Eneabba heavy mineral sand rutile, zircon, ilmenite deposits are located 6 km south of Eneabba, 30 km east of the Indian Ocean coastal town of Leeman and approximately 300 km north of Perth in Western Australia. Individual deposits, resources and stockpiles in 2022 include: Adamson, Allied, Brandy Flat, Depot Hill East and North, IPL Central, North and South, MSP By-Product Stockpile, North Mine, Northern Leases, Ocean Hill, South Tails, Twin Hills, Western Remnants and Yellow Dam. Other lower grade resources in the district are listed below.

The heavy mineral fraction also contains monazite and xenotime which contain recoverable rare earth elements, the more significant of which are neodymium, praseodymium, dysprosium and terbium representing >80% of the REE value of the deposit.

They represent heavy mineral aeolian dune sand deposits developed as fossil strandlines, now between 115 and 29 m above sea level (asl), developed over a 20 km north-south length by a 9 km width.

Mineral sand mining started at Eneabba in 1977. The operations were acquired by Iluka Resources in 1988, who continued mining until 2013. The closure was due to the collapse in demand for heavy mineral sands, although significant resources remained. The increased demand for Rare Earth Elements has resulted in a recommencement of operations to firstly reclaim a REE bearing monazite- and xenotime-rich mineral stockpile that was currently stored in a former mining void at Eneabba. This commenced in 2020 and produced a mixed monazite-zircon concentrate, with the monazite fraction at ~20%. The second phase has involved constructing a concentrator to separate the monazite and zircon streams, producing a ~90% monazite concentrate.

The Eneabba deposits are located within the North Perth Basin, a deep linear trough of sediments, extending from the south coast of Western Australia, to north of the Murchison River, adjacent to and west of the Darling Fault. The basin contains a number of high-grade beach, dune and swale heavy mineral deposits extending from Capel in the south to Eneabba in the north. The Eneabba deposits were probably formed from the Late Tertiary to Early Pleistocene on beaches cutting into Jurassic basement sediments. Mesozoic sediments are the immediate provenance of the heavy minerals which originated from the Archaean gneisses of the Yilgarn Craton to the east. It appears that the sands were transported from the hinterland by a series of streams, although the best concentrations of economic interest are located close to to two major palaeo-drainage channels.

A series of palaeo-shorelines were formed in a north-facing bay ranging from 85 to 128 m above the present sea level. There are at least 10 main strandlines at Eneabba. During the formation of these strandlines the palaeo-shoreline was straight, basically following the current 120 m asl contour. Each palaeo-shoreline represents a stand-still event during regression of the sea. The higher level strandlines from 115 to 91 m asl terminated at the southern end of the palaeo-Eneabba Bay against an erosion escarpment. A series of headlands persist further westwards below cover to as low as 29 m asl and probably correlate with those at the Jurien Bay deposits 50 km to the south. The stand-still events have resulted in well-developed platforms cut into the underlying sediments and in some instances accumulation/concentration of heavy minerals to form strandline deposits. The Eneabba Shoreline has also been correlated with the Yoganup Shoreline in the south of the Perth Basin. Following the strandline deposition of heavy minerals, several dune deposits have also been formed. At Eneabba,these dunes occur to the NE of the palaeo-shorelines from which they derive their heavy mineral content. Typically, dune mineralisation is of lower in grade but more extensive in volume than strandline mineralisation.

The highest grade concentration of heavy minerals occurs on their southern sections and is interpreted to be the result of sorting by strong southward flowing longshore drift currents.

The highest level economic strandline is at 115 asl and is characterised by a very high 50 to 70% zircon HM assemblage and only 20% ilmenite. In contrast to the other 10 strandlines between 109 and 29 m asl which carry around 50% ilmenite and generally <30% zircon within the HM assemblage.

The following trends are evident across the district:
• Zircon generally decreases with the lower level strandlines, from east to west;
• Zircon peaks on the 115, 82 and 30 m asl strandlines;
• There is an increasing level of trash HM, particularly magnetic fractions, in the lower strandlines;
• Rutile and ilmenite grades are relatively consistent, except at the 115 m asl strandline;

A study of the 109 m asl strandline revealed the following trends:
• Zircon, ilmenite and rutile all increase from west to east;
• Zircon and rutile both increase from top to bottom, except on the eastern margin of the strandline where the zircon content is the highest;
• Both magnetic and magnetic trash heavy mineral trends are the converse of zircon;
• The vertical enrichment of ilmenite is less well defined. Its density is lowered as its TiO2 content increases. The TiO2 content varies
   from 63% at the top and to the west and 56% to the east and base of the strandline.

From the start of mining in 1974 to 1985 production was - 0.9 Mt Rutile, 2 Mt Zircon, 3.5 Mt Ilmenite, 65 000 tonnes Monazite.
Resources in 1985 were 3 Mt Rutile, 5 Mt Zircon, 15 Mt Ilmenite.
Overall the deposit is estimated to contain more than 25 to 30 Mt of recoverable heavy minerals.
Production in 1985-86 was 13.8 Mt @ 6% HM, for 79 192 t Rutile, 291 267 t Zircon, 371 179 t Ilmenite, 13 438 t Monazite.

JORC compliant Mineral Resources remaining as at 31 December, 2021 (Iluka Resources Reserves and Resources Report, 2021) were:
  Measured + Indicated + Inferred Mineral Resource - 526 Mt @ 5.3% HM, 16% clay, comprising 27.9 Mt of heavy minerals;
    The HM fraction comprises - 45% ilmenite, 12% zircon, 7% rutile, 1.2% monazite + xenotime.
NOTE: Other than the MSP By-Product Stockpile (detailed below) the monazite + xenotime fraction of the resources varies from 0.2 to 1.1% of the heavy minerals which vary from 4.4 to 12.5%.
The Mineral Resources of rare earth element rich MSP By-Product Stockpile, comprises at 31 December, 2021:
  Measured Resource - 0.68 Mt @ 84.0% HM, 3% clay, comprising 0.57 Mt of heavy minerals;
    The HM fraction comprises 32% ilmenite, 26% zircon, 0% rutile, 21.4% monazite + xenotime.
  Indicated Resource - 0.24 Mt @ 78.5% HM, 4% clay, comprising 0.19 Mt of heavy minerals;
    The HM fraction comprises 35% ilmenite, 33% zircon, 0% rutile, 14.6% monazite + xenotime.
  Inferred Resource - 0.06 Mt @ 69.4% HM, 5% clay, comprising 0.04 Mt of heavy minerals;
    The HM fraction comprises 38% ilmenite, 29% zircon, 0% rutile, 13.2% monazite + xenotime.

The Ore Reserves of the same stockpile as of 31 December, 2021, after mining 0.03 Mt in 2020, were:
  Proved + Probable Reserve - 0.91 Mt @ 83.1% HM, 3% clay, comprising 0.76 Mt of heavy minerals;
    The HM fraction comprises 33% ilmenite, 28% zircon, 18.6% monazite + xenotime.
NOTE: Mineral Resources are inclusive of Ore Reserves

Other resources in the Eneabba district are reported by Image Resources NL in an ASX Release of 11 March 2022 for their Yandanooka, Drummond Crossing, Durack, Thomson, Corridor, Robbs Cross and Ellangail deposits. These deposits are located within 10 km to the SE and west of the town of Eneabba, to as far as 60 km to the NE.

JORC compliant Mineral Resources in these deposits total:
  Measured + Indicated + Inferred Mineral Resource - 199 Mt @ 2.8% HM, 14% slimes, comprising 5.5 Mt of heavy minerals;
    The HM fraction comprises - 60% ilmenite, 12.7% zircon, 6.7% rutile.

The most recent source geological information used to prepare this decription was dated: 2022.     Record last updated: 6/4/2022
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd.   Unauthorised copying, reproduction, storage or dissemination prohibited.

  References & Additional Information
   Selected References:
Lissiman J C, Oxenford R J  1975 - Eneabba rutile-zircon-ilmenite sand deposit, W.A.: in Knight C L, (Ed.), 1975 Economic Geology of Australia & Papua New Guinea The AusIMM, Melbourne   Mono 5 pp 1062-1070
Shepherd M S  1990 - Eneabba Heavy Mineral Sand placers: in Hughes F E (Ed.), 1990 Geology of the Mineral Deposits of Australia & Papua New Guinea The AusIMM, Melbourne   Mono 14, v2 pp 1591-1594

Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge.   It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published.   While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants:   i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and   ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.

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