The Stratoni polymetallic ore consists of stratabound replacement mineralisation hosted within marble horizons and may be termed a distal skarn. The mineralisation was emplaced by hydrothermal fluids driven by a granodioritic intrusive which was intruded some 30 million years ago. The mineralised zone is often referred to as the Stratoni-Piavitsa belt, and the total sulphide content of this belt prior to mining has been estimated at 25Mt. The deposits consist of massive sulphide carbonate and aplite replacement, restricted to two Marble horizons, interlayed with biotite gneiss and schist. The model therefore requires two components; marble horizons that have been thickened and structurally prepared by thrusting and folding prior to the introduction of mineralising fluids and; a structural architecture which has allowed the channelling of fluids from a magmatic source to the chemically reactive marbles. Exploration uses these two elements as a guide to identifying potential new ore zones.

The massive sulphide mineralisation has a relatively simple mineralogy, and the most abundant ore minerals are pyrite, sphalerite, galena, arsenopyrite and chalcopyrite. The dominant exploited minerals historically have been sphalerite, pyrite and galena; the ore is often abbreviated to BPG from the old notation blende, pitch, galena. The ore is also gold bearing, mostly associated with the arsenical pyrite and arsenopyrite. Quartz, calcite and minor rhodochrosite form the gangue ........

Mining was a combination of transverse and longitudinal drift-and-fill methods with rock breaking by conventional drill and blast. The drifts are then filled with cemented tailings (hydraulic fill) from surface. Ground support varies based on stopes size and ground conditions, utilizing a combination of steel sets, wiremesh, rock bolts and shotcrete.

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