The Jacobina gold district is defined by a 40-km long belt that extends from Campo Limpo, in the south, to Santa Cruz do Coqueiro, in the north. The vast majority of significant gold mineralization occurs within the matrix of the conglomerates; these include the Canavieiras, Morro do Vento, João Belo, Serra Branca deposits as well as other minor occurrences.

The gold mineralization found at Jacobina occurs as two styles of mineralization (Texeira et al, 2001):
• Conglomerate-hosted placer gold mineralization (the most important mineralization type in the Jacobina district)
• Post-depositional gold-bearing stockwork, shear zones, and associated extensional quartz veins. These styles of mineralization are relatively minor and do not contribute to the established resources at Jacobina.

CONGLOMERATE-HOSTED PLACER GOLD MINERALIZATION
Conglomerate-hosted deposits contain very fine grains of native gold, typically 20 to 50 µm in size, hosted in the matrix of the conglomerate. Gold may also be associated with rounded pyritic aggregates believed to be of sedimentary origin. There are no other significant elements present, with detailed studies of the reef chemistry showing only very minor enrichment in iron, titanium and uranium in some reefs associated with rounded grans of uraninite, ilmenite and rutile. Mineralization is typically hosted by well sorted, clast-supported conglomerate and may comprise micro-fractured, gold-bearing, recrystallized, silicified, and pyritic conglomerate units of the Serra do Córrego Formation, with a greenish fuchsite matrix and common hematite coatings along shear planes, joints, and fracture surfaces. Gold mineralization does not display a correlation with the pyrite or fuchsite content of the rock, although well-mineralized reefs are typically enriched in hematite and may contain red colored, oxidized pebbles.

POST-DEPOSITIONAL GOLD-BEARING STOCKWORK, SHEAR ZONES AND EXTENSIONAL QUARTZ VEINS
This group encompasses gold-bearing extensional quartz veins and veinlets related to semiconcordant shear zones hosted by quartzites, andalusite-graphite-quartz schists, and local conglomerates of the Rio do Ouro Formation (e.g., Goela da Ema, Biquinha, Cercadinho and Guardanapo gold workings). This style of gold mineralization is a very minor volumetric component at Jacobina and does not contribute significantly to the mineral resource. The main hydrothermal alterations associated with this style of mineralization are silicification, sericitization, chloritization, and pyritization (locally with chalcopyrite), and local tourmalinization.

The ultramafic and mafic rocks also host mineralization as narrow shear zones up to 4 m- thick in north-south oriented ultramafic sills and dikes, close to their footwall and hangingwall contacts with the hosting quartzite and conglomerate units of the Serra do Córrego, Rio do Ouro, and Serra da Paciência Formations. The mineralized shear zones are characterized by the development of gold-bearing quartz veins and/or stockwork. The main hydrothermal alteration types are silicification, fuchsitization, pyritization, and sericitization, with local tourmalinization. A number of examples of this group are known at the mine sites and surrounding areas (Canavieiras, Itapicurú, Serra do Córrego, Morro do Vento, and João Belo), and at Serra da Paciência (Mina Velha, Várzea Comprida, Ciquenta e Um, Cabeça de Nego and Milagres gold workings), in the north. This style of mineralization does not contribute significantly to the mineral resource at Jacobina.

ALTERATION
The overprinting hydrothermal alteration event at the Jacobina deposit consists of pyrite, pyrrhotite, quartz, chrome-sericite (fuchsite), chrome-rutile and chrome-tourmaline. The chromium-rich nature of this alteration assemblage is attributed to leaching of the maficultramafic intrusive rock by circulating hydrothermal fluids.

Jacobina utilizes the sublevel longhole stoping (SLS) method without backfill to achieve an average production rate of approximately 6,500 tpd from the ramp-accessed underground mines; these include João Belo, Canavieiras, Serra do Córrego, Morro do Cuscuz, and Morro do Vento.

Production drill holes vary from 76 to 112.5 mm in diameter and are drilled using three types of fan drills; these include the Solo 5 7F, the Solo DL 420, and the Solo DL 421. For the most part, drill holes are no longer than 25 m, which helps control deviation. Backfill is not required for the SLS mining method as the stopes are supported by pillars left in place. However, development waste is increasingly being deposited in underground voids. Ramp access to the mineralized zones allows for a high degree of flexibility.

Yamana is currently reviewing alternative mining methods and testing the suitability of the Jacobina tailings for paste fill or hydraulic fill applications. The results will be considered in a conceptual study that will evaluate the potential for constructing a fill plant at Jacobina. The use of cemented rock fill is also being evaluated. Alternative mining methods and the use of backfill is likely to increase mining extraction and has the potential to increase conversion of measured and indicated mineral resources to mineral reserves.

The Jacobina mineral processing plant uses conventional gold processing methodologies to treat run-of-mine (ROM) material from the underground mines. Comminution comprises three stages of crushing followed by wet grinding. Within the grinding circuit, gravity concentration of gold is performed on a bleed stream of classification cyclone underflow.

Rejects from the gravity circuit are returned to the grinding circuit. The cyclone overflow is sent to leaching in a conventional cyanide leaching process, and gold extraction from the leach solution is performed by carbon adsorption in the CIP tanks. Gold is stripped in an elution circuit and final gold recovery is performed in an electrowinning circuit. The sludge and solids from electrowinning are dried and smelted in an induction furnace to produce doré bars. The overall gold recovery in 2019 was 96.7%.

The mineral processing plant at Jacobina is currently being optimized to support a daily production of 6,500 tpd a ........