EXPLORATION ’95 — Brazilian Res. seeks gold, diamonds in

As economic reforms take hold, Brazil is becoming the focus of a new Latin American gold rush.

Quick to recognize the potential for gold and diamonds in the Amazon basin, Brazilian Resources (CDN) has acquired a number of promising concessions in the northern part of Mato Grosso state.

About 160 km north of the town of Aripuana, the company holds the Cedro Bom I and II gold concessions which cover some 20,000 hectares.

The Cedro Bom II concession was the site of placer gold mining by garimpieros from 1980 to 1990. Twelve tonnes of gold (about 400,000 oz.) is reported to have been recovered from the alluvial workings.

Geologically, the property is in the middle of the Central Brazilian Shield. Based on satellite interpretation, recent airborne geophysical surveys and limited ground work, a major (1.5-2-km-wide) east-west-trending zone of sheared and altered Archean volcanic rocks has been located on the concessions. The shear zone may be related to a major structural break which crosses the northern portion of the Cedro Bom II concession. The widespread occurrence of alluvial gold on the concessions (values up to 2.7 grams per tonne), combined with significant results ranging from 2.09 to 11.32 grams gold in fresh rock at Filao ( a showing just outside of the concessions), leads Brazilian Resources to believe that the properties have good potential to host a lode gold deposit.

“This is a typical Archean shield area,” Brazilian Gold’s geological consultant William Pearson told The Northern Miner. “We’re looking for a major gold deposit associated with an Archean structure.”

The company recently embarked on an 8-hole, 2,500-metre drill program to test several airborne electromagnetic conductors associated with the east-west-trending shear zone. As a result of access problems in the current rainy season, most of the drilling will focus on targets in the southeastern portion of the property. At presstime, four holes had been completed and, according to Pearson, they contain lots of quartz veining, potassium alteration and shearing. Assay results are pending.

The company also plans to evaluate the alluvial potential of the concessions. Elsewhere in Mato Grosso, Brazilian Resources holds the 81,000-hectare Juina property 550 km northwest of Cuiaba. This large area is underlain by Archean to Early Proterozoic rocks. Exploration activities to date have been limited to shallow prospecting and the monitoring of garimpiero work. In addition, the company controls the 2,200-hectare Alto Paraguai diamond concession, situated 140 km northwest of Cuiaba, and along the Paraguai River. The property has been the site of intense garimpiero activity for diamonds over the past few years.

The slow, meandering nature of the Paraguai River and the sedimentology of the river gravels indicate that the alluvial diamonds are likely derived from a relatively local source. The corporation has completed a preliminary interpretation of satellite LANDSAT (satellite) imagery, which shows a number of circular features that may reflect a cluster of kimberlite pipes. A helicopter-borne geophysical survey over the property has been completed, and several targets which appear to be circular features and paleo channels have been outlined. These areas will be drill-tested later in the year.