Mercury in chondrites

The Hg abundance has been determined in chondritic meteorites by neutron activation and separation by volatilization over a series of temperatures ranging from 110° to 1200°C. Hg is highly fractionated between classes of chondrites and within the classes themselves. Most hypersthene chondrites have Hg concentrations between 0.01 and 1.0 ppm; bronzite chondrites, between 0.24 and 7 ppm. Enstatite chondrites have low Hg contents similar to hypersthene chondrites. Carbonaceous chondrites have Hg contents as high as, or higher than, the bronzite chondrites. There appears to be a correlation between the total Hg content and the Hg released at temperatures above 450°C. There is also a parallel between the K-Ar ages and the Hg/Arp36, ratios. Both these observations, if substantiated by additional measurements, should prove relevant to the thermal history of meteorites.