From 1890 to 1920, underground graphite mining was practiced in New York and Pennsylvania. From 1942 until the end of World War II, only open-pit methods were used because working weathered rock was relatively easy. During World War II, graphite was mined underground at Dillon, Montana, but mining ceased shortly after because it was too costly to compete with Sri Lankan graphite. Madagascar operations are entirely open pit, but underground mining is practiced in Bavaria, Korea, Mexico, and Sri Lanka because of the depth and physical characteristics of the deposits. Mexican underground mining operations are 100–400 m below the surface, measured on the angle of the vein. Some of the older mines in Sri Lanka reached depths over 450 m on a vertical plane. For years, mining operations in Sri Lanka were primitive, and ore extraction was slow and cumbersome. The mines were mechanized after World War II. Madagascar operations also were primitive because low labor costs prohibited mechanization. After 1938 the mines began to use mechanical equipment to remove the overburden, and bulldozers and tractors easily removed the graphite-bearing schists. If you are looking for high quality, high purity, and cost-effective graphite or require the latest price, please email contact mis-asia.