Field criteria are needed to help the prospector recognize a potentially expansible shale, clay, or slate. Certain criteria have proven useful in California even though the physical-chemical mechanisms of expansion are not. thoroughly understood. Three conditions must be satisfied before expansion can take place. The raw material must partially fuse at a low temperature (1800-2000°F.). … Read more

Within recent years portable seismic refraction units have found their place in the industry for shallow investigations. Completely portable, relatively inexpensive and of proven accuracy, the portable refraction seismograph is an electronic tool in an electronic age. The seismic refraction theory is based on the ability of various materials to transfer shock waves at different … Read more

Operating geology may not seem as exciting and glamourous as exploration, especially to recent graduates, but it has its advantages as listed below: Stability: Exploration is generally the first activity curtailed in recessive periods. Satisfaction: The results of good work are visible sooner and more often. Family life is relatively normal. Geological work at an … Read more

The Louvicourt deposit is proving to be a very large one. Reserves now stand at approximately 30 million tons and, more importantly, the deposit contains some impressive widths of exceptionally high grade Cu-Zn-Ag-Au mineralization that should ensure its profitability in virtually any future metal price scenario. Regional Setting The Louvicourt deposit is located approximately 15 … Read more

Carbonates are a very rare and volumetrically insignificant family of igneous rocks composed mainly of carbonate minerals, and normally are described in terms of their habits (intrusive) and composition (mineralogy). No other association of igneous rocks exhibit as great a diversity of rock types and intrusive habit. They vary in shape and size with depth … Read more

The Grasberg copper-gold orebody is contained with a young igneous complex of dioritic composition which intrudes limestones of the Tertiary New Guinea Group. Alteration is typical of porphyry copper deposits worldwide except that higher grade primary chalcopyrite with significant gold values is associated with a centrally located zone of strong quartz stockwork.   The Grasberg … Read more

Rare earth element (REE)- and gold-bearing breccia pipes are a potentially significant economic target in the Pea Ridge iron ore mine, Washington County, Missouri. The Pea Ridge deposit is one of eight known volcanic-hosted iron ore deposits in the Middle Proterozoic St. Francois terrane, which are similar to the Olympic Dam-type deposits of Australia. Total … Read more

Concentrations of minerals between 3.5 and 5 specific gravity such as ilmenite, rutile and zircon in large accumulations of sand constitute “heavy mineral” placers. Two fundamentally different modes of formation characterize “trap” and “bed” placer variants. Smaller and generally higher grade trap placers form during sediment erosion or reworking. Because of their smaller size, they … Read more

Red Dog is a Mississippian to Permian aged sulfide deposit located in the western Brooks Range north of Kotzebue, Alaska. It belongs in the family of black shale hosted sedimentary exhalite deposits but lacks classic sulfide sedimentary textures. Pervasive silicification, and a significant portion of the mineralization, is replacement in nature. An extensive feeder vein … Read more