Mineral Exloration Research Papers - Academia.edu (original) (raw)

الطرق الكهربية لها تطبيقات كثيرة حيث تستخدم فى البحث عن الفلزات والمعادن والمياه الجوفية وتستخدم أيضا بدرجة متزايدة فى الجيولوجيا الهندسية Engineering Geology، حيث تستخدم قياسات المقاومة النوعية لإيجاد عمق صخور الأساس Bed Rocks، وكذلك فى... more

The discovery and development of high sulphidation gold deposits in the Andean Volcanic Belt of Chile and Peru in the 1980's and 1990's has defined over 200 million ounces of gold worth over a quarter trillion dollars. These gold systems are one of the most sought after types of gold deposits by exploration teams around the world today. In the 1990's the author visited many of the high sulphidation alteration systems worldwide including the historic Chinkuashih gold district in northern Taiwan to evaluate the exploration potential of that district. While production records are incomplete, it is believed that over three million ounces of gold were recovered from gold-enargite-sulfide ores. As a high sulphidation gold system, Chinkuashih is somewhat unique in that the host rock for a majority of the mineralization consists of interbedded Miocene sandstones and shales which were intruded by Pleistocene calc-alkaline plugs, sills and dikes. These host rocks were silicified and subsequently went through multiple brecciation and phreatic explosive events with precious metal mineralization episodes. Exploration potential remains in this district for additional high grade gold orebodies hosted in vuggy silica and brecciated silica surrounding the intrusive plugs and historic high grade veins that were mined in the past. Resistivity signatures need to be carefully interpreted to discriminate between massive vuggy silica-alunite alteration zones which may contain additional ore bodies from that of the host sandstones.

- by Michael Thomsen
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- Mining, Gold Mineralization, Mineral exploration, Mineral Resources

The Geochemical characteristics of geophagic clays from Calabar and Okon-Eket were evaluated to determine their quality and the possible health effects of their consumption. The study involved questionnaire administration to geophagic adults to determine justification and clay preferences, determination of physico-chemical properties, geochemical analysis of major and trace elements using ICP-MS technique and XRD aided mineralogical determination. Twenty geophagic clay samples were randomly obtained from markets and clay mines within the study areas and were air-dried and pulverized prior to analyses. Medical Records from clinics in the areas were also mined to ascertain the prevailing medical conditions in the study areas. Geophagic clays consumed are mined from riverbeds and valleys, mainly by digging. Sun-drying, baking and burning are the heat treatments applied to the clays and they are often consumed without further processing. The geophagic individuals propose relief from gastrointestinal problems, topical application to cure skin infections and cultural justifications as reasons for the practice. Results of analyses revealed a pH range of 6.5-7.0 for consumed clays, relatively high concentrations of Fe2O3 (0.64-7.74%), Al2O3 (14.32-27.31%) and SiO2[calculated] (65.77-78.89%); and concentrations of Cu (9.1-23ppm), Pb (16.7-55.6ppm), Zn (13-148ppm), Ni (11.1-46.4ppm), Co (1.8-21.7ppm), Mn (16-338ppm), As (BDL-15ppm) and Cd (BDL-0.2ppm) exceeding the recommended dietary intake by humans. XRD revealed major mineral phases as quartz and kaolinite, and minor phases as montmorillonite and muscovite. The toxic concentrations of the trace elements are probably responsible for or contribute to the prevalence of hypertension, cardiac failures and gastrointestinal problems within the study areas. The kaolinite present in the geophagic clays make them suitable for use as traditional antacids but the toxic trace element concentrations and significant quartz content will mask the beneficial effects of kaolinite and hence, the clays would cause more harm than benefit to the consumer.
Keywords: Geophagy - Geochemical evaluation - Trace elements - Mineralogy