A New Strength Measure for Ordinary Chondrites

A new strength measure is proposed which is siutable for small rocks with high scarcity values such as extraterrestrial samples. It is defined as the rate of excavation on a sample surface by a 2mm-diameter steel rod attached to an ultrasonic machine. The measure is named vibrational fracturing rate that correlates well with the relative hardness of common minerals (quartz, olivine, anorthite, calcite and talc). Values of the vibrational fracturing rate for three ordinary chondrites, Yamato-74191 (L3), ALHA77231 (L6), and Yamato-75258 (LL6) are 0.02,0.12 and 0.23mm/min, respectively. Samples studied are classified on the basis of the present strength measure as follows : 1) Yamato-74191 (L3), olivine, anorthite, and basalt, 2) ALHA77231 (L6), calcite and serpentinite, and 3) Yamato75258 (LL6) and talc. The strength of ordinary chondrites represented by the vibrational fracturing rate seems to be controlled mainly by fine particles embedded between large grains. No lithification by high temperature sintering of large grains is observed under the scanning electron microscope.