Petrographic thin sections are an essential component of mineral exploration. Yet, it’s increasingly overlooked as trendier technologies come to the forefront. Without the detailed information provided by precise thin section analysis, core logging loses most of its value and usefulness.
The origin, composition, and history of a specimen can only be accurately determined by a carefully prepared and analyzed thin section. Thin section analysis provides critical information about the sample such as the paragenesis of its constituents. Only by this detailed, accurate understanding of a core sample can determinations be made regarding the viability of the deposit.
Optical mineralogy from thin sections allows for precise, detailed information regarding the composition, metamorphism, and paragenetic history. It allows for the viewing of both structure and microtexture.
Sadly, classical mineralogy is being increasingly overlooked as newer technologies are developed. However, these technologies do not replace petrographic thin section analysis. Colleges and universities are not putting the emphasis on this basic building block of the geologic sciences. Students are neither being taught the importance of mineralogy and its sister sciences of geochemistry and petrology, nor how to perform these core skills.
A disturbing trend in petrology is the outsourcing of thin section preparation to foreign countries. In such cases, sections are mass produced without thought to quality or usability. Sections will often be wedged or improperly polished. Colors will be misrepresented by photomicrographs taken of poor quality sections, and accurate identification of minerals will be difficult.
Using a quality petrographic service may cost more up front, but the end result will pay off many times over. Poorly prepared samples are often deformed, and interesting minerals removed during the grinding process, rendering samples useless. Laser ablation and electron microprobes can cost thousands of dollars. Going into the field to collect core samples is equally pricey. A domestic laboratory employs the highest standards and uses only state-of-the-art equipment for thin section preparation.