The genesis of the deposit is thought to be mineralogical replacement or molecular substitution. As such, the process occurred when a fine-grained dolomite CaMg(CO3)2 was substituted by a coarse-crystalline magnesite MgCO3. The replacement, when taking place in geological past, likely included several phases of progressive influx of magnesium (Mg) rich fluids into existed dolomite sediment.

On the molecular basis, the incursion resulted in a near complete removal of Ca+2 from chemical structure of the sediment and a fill up of available vacancies with Mg+2. The above chemical process was accompanied by a textural transformation, where original fine-grained layout of dolomite molecules was transposed into coarsecrystalline texture of newly formed magnesite.

When viewed on a large scale the deposit is a relatively homogenous, high-grade orebody. Its appearance is well defined by a white to light-grey colour and remarkably evident crystalline texture of the magnesite rock. Closer examination, predominantly by chemical analysis, have identified that broad irregular zones of contaminants occur through such forms as veining, in-filling of fractures and within the magnesite matrix itself. The value of these contaminants and the form in which they occur play a key role in determining whether the material is considered as ore or waste.

The components of vein material are generally fine-grained pyrite and/or aphanitic white dolomite. Veins occur as i ........

At Mount Brussilof, commercial scale mining started in the second quarter of 1982 and has increased dramatically since then. The Mine is an open pit development and operates year round. Annual magnesite production is approximately 230 kt.

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