The Toongi deposit is centred on a trachyte outcrop that forms one of several alkaline volcanic and intrusive bodies of Jurassic age in the region (formed approximately 205 to 140 million years ago). The elliptical-shaped body has approximate dimensions of 850m east–west by 550m north–south. The deposit forms a low irregular topographic rise and has a depth extent of 115m below surface.

The orebody is dominantly a massive, fine grained microporphyritic trachyte comprising more than 80% feldspar, albite and aegirine in roughly equal amounts. The remainder of the rock is made up of opaque minerals. Extensive mineralogical studies indicate that the ore minerals contained in the deposit are extremely fine-grained, being less than 100µm in size (and generally less than 10µm), and uniformly distributed throughout the rock mass. The bulk of the ore metals are hosted in complex Na–Ca Zr–Hf–HREE silicate phases (eudialyte like). The dominant Nb (and Ta) mineral is close to NaNbO3 (natroniobite) in composition. Separately bastnasite hosts the light rare earth metals.

The deposit contains elevated levels of the metals zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), yttrium (Y) and rare earth elements (REEs) – lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). The orebody also contains uraniu ........

Mining of the ore deposit will take place in a single open pit, using drill and blast methods to fragment material that will then be transported to the Run-of-Mine (ROM) Pad for crushing and grinding.

The scheduled 20-year mining quantities include 1.73 Mt waste and 18.9 Mt ore, indicating a waste: ore strip ratio of 9.1%. The pit is mined in stages with the initial 10 years of production sourced from the western half of the pit, Stage 1a (west) and Stage 1b (east) mined from year 10, resulting in increased waste movements from the commencement of Stage 1b.

Articulated dump trucks have been selected to allow flexibility while working in the rugged operating conditions when mining consists of benching out a hilly terrain and hauling downhill. Articulated haul trucks will also offer the flexibility to be utilised as a part of the pre-mining construction activities such as pond excavation, bund, run of mine stockpile are (ROM pad) and tailings storage facility construction.

The trucks will be loaded by a front-end loader (FEL). It is anticipated there will be five trucks hauling ore to the ROM pad (2,800 m from pit edge to ROM pad) and three trucks hauling waste material to the waste dump (950 m from pit edge to the waste dump). Given the low waste/ore ratio, there is minimal waste and minimal selective mining required. An FEL rather than an excavator will be the prime loading tool, providing a cheaper, more sustainable, and versatile solution. ........

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