NO. 428 SULPHUR BANK MINE - This sulphur mine also became one of the most noted quicksilver producers in world. First worked for sulphur in 1865, in four years it produced a total of 2,000,000 pounds - reopened and developed for quicksilver in 1873, it is credited with total output of 92,400 flasks, and was an important producer in World Wars I and II.
Intersection of State Hwy 20 (P.M. 29.5) and Sulphur Bank Rd, 1.5 mi S of Clearlake Oaks
We found no plaque at the location that was listed in the guidebook.