There are no ages for Sphalerite at Plumas-Eureka Mine (Mammoth Mine; Eureka Peak Mine; Rough And Ready Mine; Washington Mine; Seventy-Six Mine; Lawton Vein; North Vein; Eureka Vein; Eureka Claim; Director Claim; Director 1 Claim; Director 2 Claim; Oceola Claim; Oliver Claim; Johns Extensio, Johnsville, Johnsville District, Plumas Co., California, USA