Potassium-argon analyses of P-207 in twenty-four laboratories and rubidium-strontium analyses in ten laboratories indicate that for material of this typo the average interlaboratory precision for KAr ages is 2.6% and for RbSr ages is 3.4%, and the average intralaboratory precision for KAr ages is 1.6% and for RbSr ages is 2.9%. ?? 1967.
Additional publication details
KAr and RbSr measurements on P-207, the U.S.G.S. interlaboratory standard muscovite