The Yaoure Gold Project is located in central Côte d’Ivoire in West Africa, 40 km northwest of Yamoussoukro, the political capital, and 270 km northwest of Abidjan, the commercial capital of Côte d’Ivoire.
The Yaoure Gold Project is located within a rural area 40 km northwest of Yamoussoukro, 22 km east-northeast of the city of Bouaflé and 5 km west of the Kossou dam. The project site is accessed by paved national and main roads, with the last 5 km section of the primary access being gravel.
The forest-savannah mosaic landscape of the Yaoure exploration licence area is dominated by the Mount Yaoure hills, away from which the terrain is mostly flat to undulating plains, which in turn give way to the north to the man-made Kossou Lake. The climate is tropical, with rainfall averaging 1,000 mm; average temperatures range from 22˚C to 32˚C throughout the year. In addition to the primary Bandama River there is a radial pattern of rivers and streams.
The population immediately surrounding the Yaoure Gold Project is estimated at about 12,500 people from several villages. The main economic activities in the area are pastoral and cultivated agriculture, forestry, artisanal mining, and fishing.
Artisanal gold mining is known to have been conducted at Yaoure (previously known as Angovia) since before 1913. From 1946 to 1969, several exploration projects aimed to assess the gold potential in quartz veins, and gold mineralisation. Modern exploration, in the form of regional soil and stream sediment geochemical sampling programme, began in 1983 with the French Bureau de Recherches Géologiques et Minières (BRGM), who defined two significant gold-in-soil anomalies. Subsequent work through to 1991 consisted of geophysics, trenching and core drilling, with a focus on the Angovia Prospect 1 which subsequently became the Compagnie Minière d’Afrique (CMA) mine.
An Exploitation Permit was granted to CMA in 1993, a feasibility study was completed in 1994, and a heap leach oxide gold mining operation established in 1999. Production continued until the mine closed towards the end of 2003. CMA reportedly extracted 1.9 million tonnes (Mt) of ore, with a mean plant feed grade of 3.9 g/t gold from three open pits. Treatment of the oxidised ore reportedly achieved a mean recovery of approximately 85%.
Amara acquired the exploration licence in 2004 and subsequently produced 54,382 ounces of gold from mining at Yaoure Central (formerly called Prospects 2 and 4) and Blangan Hill from 2008 until January 2011.
The geology of Côte d’Ivoire mainly consists of Archaean and Paleoproterozoic terranes. The coastal part of the country is largely covered by a Mesozoic-Cenozoic sedimentary basin, while Archaean rocks forming the Pre-Birimian basement occur essentially in the western part of the country. Paleo-Proterozoic terranes (Birimian) cover more than two-thirds of the country. The predominant strike is north-northeast to south-southwest, with a typical subvertical dip. The dominant regional metamorphism is greenschist facies.
The Yaoure Gold Project area lies on the eastern half of the main central Birimian-aged greenstone belt. This belt is a north-northeast trending assemblage of Paleo-Proterozoic volcanic, sedimentary and intrusive rocks located in central Côte d’Ivoire. The rock types found in the Yaoure district are for the most part mafic volcanic rocks with minor cherts, turbiditic metasediments and a fluviodeltaic formation. The volcano-sedimentary rocks were intruded by tonalite-trondhjemite-granodiorite (TTG) type plutonic rocks and undifferentiated granitoids.
The Yaoure orogenic lode-gold deposit is hosted by Early Proterozoic (Birimian) mafic volcanics (basalts), with granodiorite and mafic porphyry intrusions. Except for the northernmost portion of the currently defined mineralisation, the geology is dominated by mafic volcanics, with granodiorite and porphyry bodies, and lesser volcaniclastic and mafic lapilli tuff layers. The main granodiorite body occurs as a north-south trending subvertical mineralised intrusive stock in the northern half of the Yaoure Central pit. The northern end of the deposit is unconformably overlain by an intra-Birimian basin filled with relatively unmineralised volcano-sedimentary rocks.
The Yaoure greenstone belt was subjected to west-northwest to east-southeast directed crustal shortening during the Eburnean Orogeny. An Eburnian structure of particular importance to the Yaoure gold deposit is an arcuate, northeast trending regional fault. East dipping structures, known from the Yaoure Central open pit, suggest that the north-northeast to south-southwest fault branch passing through the Yaoure gold deposit experienced transpressive movement. Gold mineralisation at Yaoure was formed during Late Eburnian transpression and is overprinted only by minor kinking and by late brittle faulting. Mineralised structures such as the CMA are possibly splays off the faults which bound the intra-Birimian basin and the basin-bounding faults at the northern end of Yaoure could play a key district-scale control on the location of the deposit.
The metamorphic grade of the volcanic rocks at Yaoure is regarded as regional lower greenschist facies. Alteration associated with gold mineralisation includes silicification, carbonatisation, sericitisation and, less commonly, tourmalinisation, biotitisation and chloritisation. Altered wallrocks to veins typically contain up to 2% disseminated pyrite and locally up to 5%.