rhenium–osmium dating

rhenium–osmium dating, method of determining the age of the important ore mineral molybdenite; the method is based upon the radioactive decay of rhenium-187 to osmium-187. The rhenium–osmium ratio in most minerals is too low to be of general use as a dating technique, but molybdenite (molybdenum disulfide, MoS₂) has a very high ratio of rhenium to osmium; and workers have found that the osmium in molybdenite is practically pure radiogenic osmium-187. Ores as old as 3,000,000,000 years and as young as 38,000,000 years have been dated this way.