Brazil Project Generation (Troy 100% through Reinarda Mineração Ltda)

  • Troy in its search for new projects has an ongoing assessment and evaluation program targeting exploration and development opportunities throughout the country.

Andorinhas (Troy 100% through Reinarda Mineração Ltda)

  • Current drilling is focused on depth extensions of the main mineralised lodes at Mamão Underground Mine (M2/Melechete).
  • Two Company owned rigs in operation.

Project Description

The Andorinhas Project is a mineral exploration and development project located in Para State in northern central Brazil. The Andorinhas Project is 100% owned and operated by Reinarda Mineração Ltda. (RML), a Brazilian entity which is 100% owned by Troy Resource Holdings, a BVI incorporated holding company 100% owned by Troy Resources Limited (Troy), an Australian company. Troy acquired the Andorinhas Project from Agincourt Resources do Brasil Ltda (Agincourt) in November 2006 for a cost of US$10.1M.

Andorinhas Project Location Plan

The Project consists of two gold concessions; Mamão and Lagoa Seca which cover an area of approximately 20,000 hectares. The gold mineralisation occurs as several deposits hosted in Archaean greenstones of the Carajás Mineral Province. The deposits have been worked in the past as both open cut and underground operations by garimpeiro.

Exploration is focussed on the most prospective targets such as Babaçu and Lagoa Seca West. Regional exploration along the mineralised corridors will include surface soil sampling, auger soil sampling, rotary air blast (RAB), reverse circulation (RC) and diamond drilling (DDH) for resource definition.

Andorinhas Geology and Exploration Targets

The Andorinhas Project lies within the Serra dos Carajás Mineral Province which covers an area of approximately 6,000km2 in the eastern part of the Amazon Craton.

Andorinhas Regional Geological Setting

The Carajás Province was originally identified in the late 1960’s as one of the world’s largest iron-ore fields. Following the discovery of extensive iron-ore reserves within this previously unexplored, densely rainforest-covered area, numerous other metalliferous deposits have been identified including; manganese, alumina, nickel, tin, gold, platinum group elements and copper. More recently, the area has been recognised as a major copper-gold province, after the discovery of a number of world-class iron oxide, copper-gold deposits, and an emerging nickel laterite district, making Carajás an important and under-explored metallogenic province.

The Carajás Province lies at the southeastern margin of the Southern Amazon Craton, and is represented by granitoid-greenstone terrains, intracratonic basins, and high grade metamorphic complexes. The Carajás Province comprises two Archaean tectonic blocks; the northern Itacaiúnas Belt, a tectonic block that hosts the Carajás Basin, and the southern Rio Maria Greenstone Belt.

The Itacaiúnas Belt and Carajás Basin form a structural province consisting of the major east-west to northwest-southeast trending Carajás and Cinzento strike-slip fault systems.

The Rio Maria Greenstone Belt is composed largely of east, northwest, and northeast trending shear zones around dextral strike-slip faults that have affected chiefly the supracrustal rocks. Synformal structures along the shear directions, previously interpreted as synclinoria, are considered to be transpressive duplexes. The larger duplexes are related to east trending shear zones consisting of sedimentary rock cores bordered by thrust faults.

The project lies within the Andorinhas Greenstone Belt. This is a typical volcano-sedimentary sequence with a basal sequence of felsic-intermediate metavolcanics interbedded with metasedimentary rocks and an upper mafic metavolcanic dominated sequence that is metamorphosed to upper greenschist facies.

Andorinhas Greenstone Belt - Lagoa Seca Pit and Mamao Underground Mine Locations

There are two mineralised trends known as the Mamão-Babaçu trend and the Lagoa Seca trend. The shear zones follow the regional east-northeast trend.

In the Mamão area, mineralisation is hosted within sheared metavolcanics, with secondary structural deformation controlling mineralised shoots that trend in a north-northeast direction.

At Lagoa Seca, hydrothermal alteration and gold mineralisation occur within the Lagoa Seca shear zone. The shear cuts the Lagoa Seca Group, the upper unit of the Andorinhas Greenstone Belt.

The Lagoa Seca Group at the Lagoa Seca deposit area comprises meta-sedimentary and meta-ultramafic units. The high grade lenses are located at the contact of meta-greywacke lenses and hydrothermally altered meta-ultramafic rocks. Mineralisation is of two differing styles: quartz-carbonate-sulphide shear hosted reefs in the Mamão area, and disseminated sulphide mineralisation hosted within a broad shear zone at the Lagoa Seca area. In the Lagoa Seca area, drilling and surface mapping has traced a northeast trending structural zone for approximately 1.7km. Within the zone there are at least six separate shears defined and these vary from 60m to over 600m in length and range in thickness from less than 1m to over 12m. The shear zones show weak to moderate mylonitic textures with quartz-chlorite-epidote-carbonate alteration. The shears are near vertical and are parallel to sub-parallel to foliation. The sulphides associated with mineralisation are mainly disseminated pyrite with lesser amounts of pyrrhotite and magnetite. Veining is typically narrow and consists predominantly of quartz-carbonate-pyrite and carbonate pyrite veinlets. Mineralisation is related to disseminated sulphides, hosted within a broad shear zone. Gold appears to be associated with fine-grained pyrite, however higher grade gold intercepts are also associated with thicker quartz-pyrite veining.

Lagoa Seca Open Pit Geology

In the Mamão Mine area a series of stacked zones of gold mineralisation, from the base to the top of the sequence, are defined as the Maria Bonita, Arame, Melechete, M1 and M2 Lodes. The mineralised zones occur along east-northeast trending shear zones dipping -30° to -60° to the north. These shear zones are interpreted as surfaces of reverse movement that were re-activated at a later stage by normal displacement.

Lagoa Seca - Mamao Area Geology and Gold-in-Soil Anomalies

The mineralised zones present as quartz veins and veinlets that cut quartz-carbonate-plagioclase-amphibole-chlorite schist (metamorphosed mafic volcanic rocks).  The mineralised zones show a strong mylonitic foliation marked by the preferential orientation of chlorite crystals and by the alteration of quartz-carbonate-rich bands with chlorite-rich bands.  The mineral assemblage of the zones consists of pyrite, quartz, carbonate and chlorite, occurring as replacement products of the original mineral assemblage and indicates strong hydrothermal alteration. Most of the quartz veins were formed during this alteration process and are oriented parallel or sub-parallel with the mylonitic foliation. Gold mineralisation is associated with sulphide-rich fluids that percolated through the shear zones. The Melechete Lode is the principle ore source for the underground mine with ore also being mined from the M2 hangingwall zone and the Arame footwall zone.

Mamao Underground - Mineralised Lodes and Mine Development