Overview

Mine Type	Open Pit
Status	Inactive / Suspended
Commodities	Gold Silver
Mining Method	Truck & Shovel / Loader
Mine Life	...
Snapshot	In autumn 2014, the Certej project Eldorado Gold started construction works without a valid permit. After legal action and citizens’ petitions, regional authorities ordered Eldorado Gold to halt the works. A final ruling from the Cluj Court of Appeal of 2019 annulled the urban plan for the Certej mine proposal. On 17 July 2020, the Oradea Court of Appeal rejected a request submitted by Deva Gold asking for a review of a final ruling. This latest decision is final. During 2022, Eldorado Gold recorded impairment on the Certej project. The project has been presented as a disposal group held for sale as at December 31, 2023 and as a discontinued operation for the years ended December 31, 2023 and December 31, 2022.

Deposit type

• Epithermal
• Breccia pipe / Stockwork

Summary:

The Certej deposit is best classified as an intermediate sulfidation epithermal deposit based on the abundance of base metals (Pb, Zn, including Fe-poor sphalerite) associated with Au and the presence of a near neutral pH alteration assemblage of quartz-illite-pyrite ±adularia±carbonate. The related igneous rock composition and tectonic setting are also consistent with an intermediate sulfidation ore forming environment; specifically the calcalkaline andesite association and broadly extensional stress state of the magmatic arc, albeit at a distance significantly distal from the arc. Analogous terms in the literature classify similar deposits as sulfide and base metal-rich low-sulfidation epithermal deposits and carbonate-base metal gold deposits.

In the Certej deposit three main andesite phases are recognised, namely Hondol, Dealu Grozii (part of the larger Sacaramb andesite), and Baiaga. The three andesites are broadly similar in composition but the Dealu Grozii/Sacaramb andesite typically contains biotite and is coarse grained, whereas the younger Baiaga andesite is fine grained. The Dealu Grozii and Hondol andesite occur respectively on the eastern and western edges of the main Certej deposit and the Baiaga andesite is located in the centre of the deposit and at depth, and is flanked by Cretaceous and Neogene sedimentary rocks. Silvers of ophiolitic rocks (dominantly altered basalt) are localized along fault and breccia zones within the Cretaceous sedimentary package. The Baiaga andesite is interpreted to have intruded up into the sedimentary and volcanic rocks, possibly controlled by an E-W fault, resulting in upward buckling of the overlying package.

The Certej deposit is classified as an intermediate sulfidation epithermal deposit due to the Au being associated with Ag, Pb and Zn and minor Te and As, and the strong quartz illite-pyrite ±adularia±carbonate alteration assemblage. The mineralization footprint (defined by the 0.2 g/t Au cut-off) has a broad E-W orientation and is constrained between two major NW-SE oriented faults, the East and West faults. In detail the Au distribution exhibits a complex pattern controlled by a combination of structure, proximity to the Baiaga andesite and host rock type. Mineralization occurs at the brecciated contact of the Baiaga and up into the surrounding sedimentary rocks and Hondol and Dealu Grozii andesites. Some of the higher grade mineralization in particular appears to be localized by NW-SE and NE-SW normal faults that may have focussed the mineralization fluids around the Baiaga andesite. Mineralization styles include disseminations in sedimentary units, hydrothermal breccias, stockworks and disseminations at the contacts of intrusive rocks and distal veins. The Au mineralisation is associated with disseminated pyrite (with arsenic and gold-rich rims) occurring together with variable amounts of sphalerite and galena. Native gold is present but restricted to distal veins.

Both hydrothermal alteration and pathfinder geochemistry are zoned about the centrally located Baiaga andesite. A zoned alteration assemblage is recognised with a sericite quartzpyrite alteration forming a central higher temperature alteration proximal to the Baiaga andesite. Within the breccias and higher grade Au-bearing structures an adularia quartzsericite-pyrite alteration occurs. More distally to the Baiaga illite-clay-carbonate alteration develops zoning outward, particularly in the west, to a chlorite carbonate-smectite alteration.

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Job Title	Name	Profile	Ref. Date
.......................	.......................		Apr 29, 2024