MINING & OPINION — NEW HORIZONS — Geochem gaining in stature

Most mineral exploration geologists are now familiar with the use of chemical analysis of rocks, soils, plants or water in determining concentrations of mineralization in bedrock.

Historically, prospectors relied on a keen eye to note subtle changes in the color of plant leaves, stream waters and rocks (in addition to panning stream sediments for gold) to guide them to mineralization. These obvious telltale natural chemical trails revealed the presence and location of deposits at or near the surface. Mineralization that is covered by thick layers of sand, gravel or barren rock does not produce visible changes in the surface environment. Therefore, these covered deposits are much harder to find.

There was a time when prospectors and geologists did not understand the reason behind these visible changes that revealed mineralization, and it wasn’t until the middle of the 20th century that scientists began to use analytical chemistry to uncover the secrets behind these changes. This marriage of sensitive geochemical analysis with geology began to reveal changes in the natural environment that are not visible to the eye. The study of these subtle chemical patterns, revealed by systematic sampling and analysis of natural materials, led to the formation of the science of exploration geochemistry. Geologists and chemists who specialize in understanding the movement of elements in the natural environment are known as geochemists.

Advances in analytical chemistry have resulted in instruments capable of routinely detecting most elements in concentrations as low as one part per billion and, in some cases, down to parts per trillion.

It has always been the focus of geochemists to monitor the quality of sampling and analysis in mineral exploration. Various stock exchange regulatory bodies have chosen to highlight this facet of the science in the wake of several well-publicized scandals.

In 1970, geochemists in various countries formed the Association of Exploration Geochemists in order to advance the science of geochemistry as it relates to exploration and the environment and to facilitate the acquisition and distribution of scientific knowledge. Articles in the Journal of Geochemical Exploration, the publication of the AEG, continue to reveal the complexity of the natural environment and the differences that are present in different parts of the world.

Every two years, the AEG hosts the International Geochemical Exploration Symposium (IGES) to share the latest information regarding advances in geochemical exploration and element transport in the environment. The 19th IGES will be held April 11-16 in Vancouver, B.C., at the University of British Columbia. Contact Dr. W.K. Fletcher at fletcher@unixg.ubc.ca.

— The author is a member of the Association of Exploration Geochemists.