The Ouro Belo tin, gold and indium project (CAS 100%) covers an area of more than 400 square kilometres in the Goias tin province, located in the northeast of Goais state approximately 300 kilometres north of the federal capital of Brasilia. Crusader believes that this area is highly prospective for gold, tin, and indium mineralisation. Figure 1 below shows Crusader's large regional tenement holding and the target corridor for tin granites.
Figure 1: Ouro Belo regional map with target corridor highlighted
Crusader is focussing its regional exploration on structural target zones as the focus for intrusion of the tin granites. Regionally, northeast trending thrust faults appear to be a first order control on the localisation of tin granites. Within the Ouro Belo project area, the tin granites occupy a north-northwest trending structural corridor and known tin prospects occur in a corridor adjacent to the granites. These two structural orientations and the intersections of the associated fault systems are the principal focus for current exploration.
Crusader has identified a number of garimpos within the Ouro Belo tenements which are located near the intersection of a northeast trending thrust fault and a north-northwest trending fault corridor.
The Imgazeira garimpo has a disturbed area of ~ 0.5 square kilometres that was excavated during the 1980's for tin mineralisation. Workings have targeted poly-metallic tin mineralisation within a sheared metasediment zone, unlike the granite-greisen hosted tin-indium mineralisation at Manga. Quartz-iron-malachite veining up to 5 metres wide was sampled. The vein and shear zones also show potential to extend under shallow cover to the northwest.
Approximately 1.5 kilometres to the northwest of Imgazeira is a larger, water filled garimpo, known as the Mocambo prospect (Figure 2). Production figures for this garimpo are not known, however the area excavated is estimated at 200 metres long x 40 metres wide x 10 metres deep. These workings are in a kaolin altered granite. Mining was halted apparently because of the declining tin price. Anecdotal information gathered from garimpeiro's indicates that gold was recovered in small amounts with cassiterite however it was not considered to be economic to mine.
Figure 2: Mocambo tin garimpo with extensive workings. Note kaolinised granite in foreground.
Crusader is currently undertaking a program of geological mapping, structural analysis of satellite imagery and re-processing of airborne magnetic and radiometric geophysics that was acquired by the state government during 2007. The aim of the program is to identify the presence of buried tin granites and associated structural settings where the tin bearing alteration systems may be preserved but have not been exposed through erosion.
The Manga Tin/Indium Project
The Manga Tin (Sn) and Indium (In) project covers a 15km2 area of Crusader's Ouro Belo tenements in the central Brazilian state of Goias.
The Manga area has a history of tin mining and Crusader has confirmed the presence of a number of historical garimpeiro (prospector) workings. The garimpeiro workings have targeted the weathered surface regions, to a maximum depth of 4 metres, to extract tin which occurs primarily as cassiterite.
The greisens (altered granitic rocks which appear to host the Sn and In mineralisation) at surface appear to be extensive and early exploration work will focus on mapping the extents of the various greisen units.
Figures 3 & 4: Greisenised Granite sample with cassiterite (Sn mineral). Most of the known Indium concentration is associated with cassiterite, although the area boasts the type location of the unique Indium minerals - Yanomamite.
A reverse circulation (RC) drilling program has now been completed with a total of 1,001 metres drilled in 15 holes. The drilling targeted of selected sections across the mineralised greisen zone as well as some of the more important garimpiero workings. The map below shows the location of a selection of the drill holes as well as previously released results from rock samples.
Figure 5: Manga Project drill-hole locations and rock chip samples
Previously a total of 165 rock chip samples were collected to define the extensive greisen area at Manga and to assist in planning for the drilling program. Highlights of the rock chip assay results included:
MNRK068 4.99% Sn and 70.6 ppm In
MNRK227 0.17% Sn and 127.0 ppm In
MNRK277 0.99% Sn and 20.8 ppm In
MNRK299 0.68% Sn and 83.8 ppm In
