Calcite coating Mottramite stalactiteMottramite is part of what is known as a solid solution series,

Calcite coating Mottramite stalactiteMottramite is part of what is known as a solid solution series, when there exists a continuum of chemical composition between end members within a mineral family. In this case the end members oscillate between lead and copper vanadate, formed when primary ore deposits are altered by the passage of oxidising mineralised fluids. Mottramite is the copper rich end member, as evidenced by the gorgeous green colour, while orangey brown descloizite is the lead rich one. The stalactite in this unusual piece from the Tsumeb mine in Namibia has grown on a matrix of calcite and been subsequently encrusted with gemmy transparent rhombs. For size reference, the largest rhomb is over 2cm across. LozImage credit: Rob Lavinsky/iRocks.comhttp://www.mindat.org/min-2792.htmlhttp://www.galleries.com/Mottramitehttp://webmineral.com/data/Mottramite.shtml -- source link

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