Densities and Porosities of Ordinary Chondrites; Do High Porosity Meteorites Represent Regolith Materials?

Introduction: Densities and porosities of meteorites provide information about the physical properties of their parent bodies (asteroids). Recent studies report the densities and porosities of ~40 ordinary chondrite (OC) meteorites [1,2]. In this study, we present 42 additional measurements of OC densities and porosities, and provide a rigorous analysis of the errors in the method. Additionally, we investigate potential controls on OC porosity, examine the range of heterogeneity among stones of a single fall, and consider if friable OCs could be potential analogs for low-density asteroids or secondary products from higher-density asteroids. Background: The bulk volume of a meteorite consists of the volume of the mineral grains and the volume of the pore spaces. Grain volume is defined as only the volume of the mineral grains within the meteorite sample. Microporosity is the inherent porosity within the sample (on the same scale as the grain size). Macroporosity is large-scale porosity from fractures and voids caused by fracturing. Me thods: Bulk densities were measured using a modified Archimedian method [1,3], and grain densities were measured using a helium gas pycnometer [1,4]. We measured the accuracy of the pycnometer and show the grain volume measurements to be ~± 6 cm