Noun
rubidium-strontium (uncountable)
(attributive) Designating a method of geological dating based on the relative amounts in rock of rubidium-87 and its beta-decay product, strontium-87.
Rubidium-strontium dating is not as precise as the uranium-lead method, with errors of 30 to 50 million years for a 3-billion-year-old sample. Source: Internet
Rubidium-strontium dating method main This is based on the beta decay of rubidium -87 to strontium -87, with a half-life of 50 billion years. Source: Internet