Characteristics of metal particles in Apollo 16 rocks

It is pointed out that FeNi metal particles, composed predominantly of kamacite and ranging in size from less than 1 micron to more than 2 mm across, are ubiquitous in the lunar samples returned by the Apollo and Luna missions. The metal particles seldom exceed 1% of the volume of a lunar sample. However, their study has proven to be of considerable potential value in a number of aspects of lunar petrogenesis related to thermal history, equilibration temperatures, reduction processes and oxygen fugacities during magmatic crystallization and subsolidus reduction and oxidation, and the meteoritic component of lunar rocks based on Ni-Co contents of individual metal particles. Detailed studies have been conducted of the textures and compositions of the metal particles in 19 Apollo 16 rock samples representing material from the North Ray and the South Ray ejecta and/or fall-back blankets. It was found that the textures and compositions of the metal particles in the Apollo 16 rocks can be correlated with their host petrology.