Journal of Geology and Geoscience

Gold and Other Metals in the Cao Ram Area, Doi Bu District, Hoa Binh Region, Southwest of Hanoi, Vietnam

Author(s): Michael D Campbell, Roger W Lee, and M David Campbell

Mining properties located southwest of Hanoi, Vietnam in the Đồi Bù District, Hòa Bình Region were visited during January, 2014. The key conclusions of the assessment were: 1) The subject areas have not been explored in any detail for decades if not longer. The Chinese (pre- 1900s) and then later the French (pre-1960s) conducted basic reconnaissance and produced the early maps of the area. During the 1960s and 1970s, the USSR explored the area in some detail via outcrop sampling programs and some drilling, but many sites within the area of interest remain poorly investigated and untested. The general area has received only superficial investigation to date of the obvious fracture zones and associated outcropping geological structures; 2) Since the late 1980s, the Vietnamese Geological Survey and associated universities have undertaken the systematic assembly and cataloging of all available geological, geophysical, and mining information on the reported minerals present in Vietnam, almost all of which are in Vietnamese; 3) Various Government departments are involved in all mineral exploration and mining programs in Vietnam for the purpose of supporting exploration and mining and for purposes of regulating the exploration and mining activities to ensure that the health and safety of the local inhabitants, farm animals, and the local surface water and groundwater are protected for long-term use by the people of Vietnam; 4) After a review of the available literature and selected translations of the reports relating to the areas of interest (combined with the information gained during the visit of January, 2014), and based on the samples taken from outcrop, evaluated, and tested at an international laboratory, the authors have concluded that the subject areas discussed here have an unusually high potential for world-class ore bodies of precious and base metals present at shallow depths (<600 m); 5) Of the 31 samples obtained from outcrop in the Hop Hoa, Vai Dao, Lang Sen, and Lien Son areas, 42% of the total number of samples analyzed show gold values in excess of 1 gram per tonne (g/t), seven of those contain greater than 5 g/t with two higher than 25 g/t (i.e., 25.6 and 68.9 g/t). Although the high analyses might be the result of the “nugget” effect, they can show nothing about the available volume of mineralized rock surrounding the samples and their metal content until drilling is conducted to determine the horizontal and vertical extent of the zone and grade of associated precious metals and other metals; 6) The type of mineralization present in the area of interest (Au-Mn-As-Pb-Ga-Mo) indicates that other metals of economic significance would likely occur with the gold making any mining and processing design a multi-metal venture; 7) Based on sampling of the tailings at the Cam Vao Processing Plant near Cam Ram, the associated tailings pond, and adjacent creek, all three areas contain high concentrations (in environmental terms) of arsenic, cadmium, mercury, and lead. An environmental assessment should be conducted on and around the processing plant extending to and including the associated down gradient rice paddies.

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