Abstract Recent advances in geometallurgy have made nickel laterites a premier target for mining and exploration companies. Parallel to this, a series of advances in remote sensing have become available at very low cost. Two of these advances, namely better topographical data, through NASA’s Shuttle Radar Topographic Mission (SRTM), and multispectral imagery from the ASTER sensor, have been combined to aid nickel laterite exploration in central Brazil. The Conceição do Araguaia region, located in Pará and extending into Tocantins state, is part of the Neoproterozoic Araguaia fold belt. The target area covers the Quatipuru mafic-ultramafic association, which includes serpentinites (metaperidotites and metadunites), talc schists, tremolite-actinolite schists and small volumes of pillow basalts, phyllites, BIFs, gabbroic and jasperoid rocks. These are enclosed regionally by slate to phyllitic rocks. Several other occurrences of mafic-ultramafic rocks, along with Quatipuru mafic-ultramafic association are interpreted as part of an ophiolitic complex. Low-grade (greenschist) regional metamorphism is dominant. Laterization has been active since the early Tertiary, resulting in an extensive regolith cover over the older rock units. In the present work, the Quatipuru mafic-ultramafic association was examined for nickel laterite mineralization by data compilation and remotely sensed image processing and interpretation. ASTER’s multispectral visible-shortwave infrared (SWIR) remote sensing capabilities were used to map areas of prospective mineral alteration and key mineral groups. Using spectral libraries for selected nickel-bearing minerals as standards, SWIR and visible-NIR bands of georeferenced mosaiced ASTER scenes were processed by feature-oriented principal component analysis (PCA), and the results converted in mineral-abundance images, based on statistical classification and pseudocoloring. The mineral abundance maps highlight areas most likely to contain minerals of interest. Processing was performed for the whole region of interest, and for its part in the central scene alone, which covers about 85 percent of the concession areas. In both cases, statistics for PCA were conducted on a subset of the data, minimizing extraneous factors such as large drainages and urban sprawl, and then applied to the whole region. Mineral abundance maps for the area have been built into a geographic information system (GIS), along with other remotely sensed data, public-domain regional geophysics, geologic, and infrastructure data, scouted geochemistry samples, and a leveled and continuous SRTM digital elevation model. Mapping for the occurrence of mafic-ultramafic rocks was achieved by a combination of PCs 1, 4 and 2 of ASTER bands 2, 4, 5, and 8. Clusters of anomalous contents of selected minerals are draped over the digital elevation model and indicate that the northeast-dipping rock units are covered by a laterized sequence constituting the main exploration targets. This targeting exercise revealed a number of favorable sites that are currently under exploration by mining companies.

Abstract Revolutionary advances in extractive metallurgy and mineral processing and their evolutionary application have significantly altered the processing operations of mining companies over time by increasing productivity and reducing costs. Some developments have had such an impact on the industry that new types of mineral deposits can be developed and waste becomes ore. Historically, it has taken years, in some cases decades, for metallurgical developments to affect exploration strategies, largely because of limited communications between geologists and metallurgists. Seven significant advances in the extractive sciences are viewed as having the highest impact on mineral exploration and mining. These are solvent extractionelectrowinning, leach processing, bioprocessing, flash smelting, geometallurgy, energy-efficient fine grinding, and underground processing. Developments in these fields have resulted in commercialized or piloted processes that demonstrably reduce capital and operating costs and thereby increase shareholder value. Two process developments with the potential to significantly affect the industry in the future are breaking rock in tension and in situ leach of metals. The benefits of metallurgical advances to exploration include reduced processing and capital costs, as well as elimination of repeat characterizations through improved analytical instrumentation and data transfer capabilities. New ore deposits are less likely to be overlooked or underappreciated when metallurgical and processing developments are integrated into team-based exploration planning. An example of new target generation is zinc oxide ore, such as that from Skorpion, Namibia, that has been made economic by hydrometallurgical techniques. As exploration targets and discoveries become increasingly deep, the successful development of orebodies will depend in part on the ability of metallurgists to develop innovative processing methods, such as pressure leach and bioleach hydrometallurgical technologies, or developments in mineral processing. To some extent, the ore geology of a deposit may predetermine the processing methods to be applied. However, the complex relationships of mineralogy, grade, and location, plus energy, capital, and other costs make the development of new extractive techniques a virtual necessity for exploration success.