Wash. Rev. Code § 78.08.020
A mining claim located upon any vein or lode of quartz or other rock in place, bearing gold, silver or other valuable mineral deposits, after the approval of *this act by the governor, whether located by one or more persons, may equal, but shall not exceed, one thousand five hundred feet in length along the vein or lode; but no location of a mining claim shall be made until the discovery of the vein or lode within the limits of the claims located. No claims shall extend more than three hundred feet on each side of the middle of the vein at the surface, nor shall any claims be limited by any mining regulation to less than fifty feet of surface on each side of the middle of such vein or lode at the surface, excepting where adverse rights, existing at the date of the approval of this act, shall make such limitation necessary. The end lines of each claim shall be parallel to each other.
RCW 78.08.020
*Reviser's note: "this act" [1887 c 87], is codified in RCW 78.08.005 through 78.08.040; "date of the approval of this act" was February 2, 1888.