Champion Spark Plug Mine and Camp Exploration AKA Jeffrey Mine

This video takes us to the Champion Spark Plug Mine, also known as the Jeffrey Mine, near Bishop CA. on 4-30-2018. The rugged trail climbs 3100 feet over 3.5 miles through Jeffrey Mine Canyon. There is a well preserved miners camp about 2 miles from the trail head. The actual mine is another 1.5 miles up the mountain making the round trip about 7 miles long.
It was here that in 1920 Dr. Joseph Jeffrey, a dental surgeon, discovered a large deposit of Sillimanite, a mineral useful in making high quality porcelain. Sillimanite is one of three aluminosilicate polymorphs, the other two being andalusite and kyanite. The Champion company used the mineral from this mine to increase the strength and quality of the porcelain insulator portion of their spark plugs.
The mine operated from 1921 to 1945 producing 26,457 tons of andalusite/sillimanite ore valued at $184,000 and in the 1920's was the only commercial source of andalusite in the world.
The ore was transported down the mountain by 16 mules, two strings of 8 each, and 2 freighters or packers who ran the teams. The mule teams made two trips per day, winter and summer, using a pack saddle to protect them from the heavy load which consisted of a 95 pound sack of ore on each side of the pack saddle. There was a corral at the base of the trail for the mules to be cared for and also a facility to transfer the ore to trucks that took it to a loading station on the Nevada & California narrow gauge railroad and train named the Slim Princess. In Mina, Nevada the ore was transferred to standard gauge Southern Pacific Railroad trains and shipped to Detroit for processing. The Champion Sillimanite Company of Detroit, Michigan, processed the ore to manufacture high temperature refractory materials used in their spark plugs.
Sillimanite has since been replaced by a synthetic material called mullite.

Видео Champion Spark Plug Mine and Camp Exploration AKA Jeffrey Mine канала Mine Exploration and Hiking with Tom and Julie