Viburnum

VIBURNUM (EN: Viburnum; RU: Вайбернем) is the unique, according to the reserves of lead and zinc, ore region within the south-eastern part of the Missouri state (USA). The region has been discovered during the 1953, and is being developed since the 1964. The length is more than 70 kilometres along the meridional direction, with the average width of 3 kilometres. The region includes the deposits of the stratiform type: Viburnum, Magmont, Buick, Brush Creek, Fletcher, Ozark. The deposits are confined to the stratum of the dolomitic limestones since the Upper Cambrian till the Lower Ordovician with the thickness of 60-135 metres. The ore bodies of the tabular shape (the thickness is 1-15 metres, less often up to 30 metres, the length along the strike is up to 8 kilometres, the width is up to 600 metres) are embedded at the depth of 300-400 metres. The ore bodies are stretched along the reef structures, and gravitate to the layers of the sedimentary breccias. At the Ozark deposit, the ore bodies are sometimes represented as the stockworks, and are controlled by the faults, which are discordant to the stratification. The texture of the ores is interspersed, banded, and brecciated.

The main ore minerals are galena (predominates), sphalerite, chalcopyrite, and there exist pyrite, and marcasite in the insignificant quantities. The non-metallic minerals are dolomite, quartz, kaolinite, and others. The reserves of the ore are 1 billion tonnes, with 2.5-3% the content of lead, and 1% the content of zinc. The total reserves of lead within the deposits amount to 88% of the reserves within the USA (1979). The deposits are being developed to the depth of 450 metres with the seven underground mines (the productive capacity is up to 5 thousand tonnes of the ore per day, 1980), which belong to the "St. Joe Minerals" company. The "Brush Creek" and "Fletcher" underground mines are the most modern, and highly mechanized enterprises. The system for the development is room and pillar, the width of the chambers is 10-12 metres, the height is 6 metres, the width of the interchamber virgin pillars is 9 metres. The delivery of the ore from the stope to the beneficiation plants is of the conveyor type. The produce of the beneficiation plants is the concentrates of lead (70-78%), zinc (50-55%), and copper (24-28%). Along the way, there are being extracted silver and cadmium. The extraction from the ore is 98% of lead, 60% of zinc, and 60% of copper. The deposits of the Viburnum region yield more than 80% of the lead, which is being extracted within the USA (1981).