The Piskanja deposit is of continental lacustrine type, typical of many global boron deposits, and is considered to have formed within a closed basin with abnormally high salinity. The boron mineralization is most likely to have been sourced from local volcanic rocks, from which it was leached by hydrothermal fluids. Boron minerals were then deposited in sedimentary successions in lacustrine conditions through the processes of evaporation and chemical precipitation. The presence of laminated dolomitic rocks and claystone in association with borate mineralization indicates sedimentation in the deeper parts of a lake.

Most borate minerals are highly soluble in water which restricts the areas in which they form, and more importantly, are preserved. The majority of known global borate deposits have formed in lacustrine or playa lake environments in closed basins that opened up in active extensional setting near subductive plate boundaries. Rock types associated with the deposits generally include calc-alkaline extrusive rocks, tuff, limestone, marl, claystone, gypsum, continental silts and sands. The source of boron is not always the same and can be derived variously from leached marine sediments, magmatic fluids from subducted crust or from volcanic material (tuff).

The boron deposits in the USA and Turkey (which together account for around 80% of world production), are associated with continental sediments and show a continuum between hydrothermal spring ........

The geometry and depth of the mineralization identified at Piskanja lends itself to an underground mining method. This section of the report presents the results of work completed to date to determine how the mineralization will be most appropriately worked and extracted. While more detailed analysis is required and will be undertaken in due course it is the assumptions presented here that form the basis of the PEA presented later in this report.

It is envisaged that mining will be by cut and fill method and that the key underground infrastructure will comprise:

• Twin access declines from surface to the deposit: i) main haulage decline (further addressed as MHD) from surface to the floor of KZONE1 and ii) main ventilation decline (further addressed
as MVD) from surface to the roof of KZONE3;
• An underground spiral ramp connecting MHD and MVD and enabling access to all levels;
• A shaft connecting MHD and MVD to serve as an ore pass and temporary (if needed) ore stock;
• Footwall drives located below seam horizons of KZONE1, KZONE2 and KZONE3; and
• Level drives and ventilation connections between three footwall drives.

Ventilation
For the purposes of this PEA, it is envisioned that the mining operation will not utilize blasting, that all equipment will be electric (powerline or battery) and that maximum number of workers per shift in the underground facilities will not exceed 50. Having this in mind required ai ........

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