title: Rubidium-strontium relations in tranquillity base samples.
abstract: Preliminary total rock analyses disclosed a greatly different rubidium depletion between two groups of these igneous rocks, and ratios of strontium-87 to strontium-86 indicate that the rubidium depletion in these materials must have occurred during or shortly after the accretion of the terrestrial planets.
authors.forename: P M
authors.initials: PM
authors.lastname: Hurley
authors.forename: W H
authors.initials: WH
authors.lastname: Pinson