Foster retired from the Geological Survey in 1865 .
Foster devoted his attention to mineralogy and mining in Cornwall , Egypt and Venezuela , becoming a lecturer for the Miners Association and secretary of the Royal Cornwall Polytechnic Society .
Retiring from the Geological Survey in 1865 , Foster devoted his attention to mineralogy and mining in Cornwall , Egypt and Venezuela , becoming a lecturer for the Miners Association and secretary of the Royal Cornwall Polytechnic Society .