The Efemçukuru deposit is a typical low sulphidation epithermal vein deposit developed in an active fault environment resulting in numerous fragments of the surrounding country rock being included in the quartz rhodinite vein. Vein textures are typical of an epithermal system where the gold was precipitated by boiling of the hydrothermal fluids and also by chemical reaction with the surrounding wall rocks.

The Kestane Beleni Vein is a low-sulfidation epithermal vein. Early veining consisted of three or more episodes of sulphide poor quartz rhodonite gangue, followed by later multiple phases of quartz and quartz-sulphide veining. Open-space textures are present in the vein along with complex breccia textures. Sulphides consist of pyrite, sphalerite, galena, and trace amounts of chalcopyrite. The base metal and overall sulphide content of the MOS is considerably higher.

Silver content of the deposit is highly variable. The average silver grade for both the MOS and SOS is low (11.9 and 8.3 g/t), however, parts of the MOS shoot contain silver values in excess of 100 g/t. The higher grade silver zones tend to be peripheral to the high grade gold zones.

The majority of the gold mineralization is very fine-grained (0.5 to 30 microns) occurring as free grains in quartz and rhodonite gangue, and as partially locked grains in pyrite, chalcopyrite and sphalerite. Gold is also, to a lesser extent, present in galena. Higher gold grades, however, are not directly related to sulphide percentages.

Oxidation is most common in near surface intercepts; however, isolated zones of oxidized vein material can be found at all depths explored by drilling and appears to be related to faulting. Locally, vein footwall and hanging wall rocks can be oxidized to iron and manganese gossan, while only a few metres away the host rocks are unoxidized.

Efemcukuru is a high grade underground deposit with the gold occurring as free gold closely associated with sulphides. The ore is mined using conventional mechanized cut and fill along with some opportunity for longhole mining methods.

The ore is processed through a milling circuit followed by flotation to produce a flotation concentrate. A gravity circuit was used until late 2017 to remove coarse product from the concentrate. However, only around 1% of the gold reported to gravity and it was decided that operating the gravity circuit for this small amount was not economic or viable. As part of operating agreement between 2011-2012, Eldorado were transporting the flotation concentrate from the Efemcukuru mine to the Kisladag Concentrate Treatment Plant (KCTP), where it was treated in a dedicated cyanide leach plant. The gravity concentrate was refined to doré on-site. In late 2012 and 2013, the flotation concentrate was sold under contract to the spot market while the KCTP was under review to improve gold recoveries. A decision was taken late in 2013 to decommission the KCTP and continue to sell the concentrate under contract to third parties.

The flotation tailings are filtered and either placed back underground as paste fill or placed in a lined dry stack tailings facility.