A new method for the measurement of meteorite bulk volume via ideal gas pycnometry

Abstract

[1] To date, of the many techniques used to measure the bulk volume of meteorites, only three methods (Archimedean bead method, 3-D laser imaging and X-ray microtomography) can be considered as nondestructive or noncontaminating. The bead method can show large, random errors for sample sizes of smaller than 5 cm 3 . In contrast, 3-D laser imaging is a high-accuracy method even when measuring the bulk volumes of small meteorites. This method is both costly and time consuming, however, and meteorites of a certain shape may lead to some uncertainties in the analysis. The method of X-ray microtomography suffers from the same problems as 3-D laser imaging. This study outlines a new method of high-accuracy, nondestructive and noncontaminating measurement of the bulk volume of meteorite samples. In order to measure the bulk volume of a meteorite, one must measure the total volume of the balloon vacuum packaged meteorite and the volume of balloon that had been used to enclose the meteorite using ideal gas pycnometry. The difference between the two determined volumes is the bulk volume of the meteorite. Through the measurement of zero porosity metal spheres and tempered glass fragments, our results indicate that for a sample which has a volume of between 0.5 and 2 cm 3 , the relative error of the measurement is less than AE0.6%. Furthermore, this error will be even smaller (less than AE0.1%) if the determined sample size is larger than 2 cm 3 . The precision of this method shows some volume dependence. For samples smaller than 1 cm 3 , the standard deviations are less than AE0.328%, and these values will fall to less than AE0.052% for samples larger than 2 cm 3 . The porosities of nine fragments of Jilin, GaoGuenie, Zaoyang and Zhaodong meteorites have been measured using our vacuum packaging-pycnometry method, with determined average porosities of Jilin, GaoGuenie, Zaoyang and Zhaodong of 9.0307%, 2.9277%, 17.5437% and 5.9748%, respectively. These values agree well with the porosities of fragments of which have been measured using the Archimedean bead method and 3-D laser imaging. This method also may be applied to the study of rare samples in other fields (e.g., archeology and geology).Citation: Li, S., S. Wang, X. Li, Y. Li, S. Liu, and I. M. Coulson (2012), A new method for the measurement of meteorite bulk volume via ideal gas pycnometry,

Chemical and physical properties of Žďár nad Sázavou L chondrite and porosity differentiation using computed tomography

“…This suggests that a large amount of pores is not detected by CT. Nevertheless, CT brings a different perspective to the porosity in terms of morphology and distribution of air cavities in 3-D. Also, the bulk volume obtained from CT is more precisely determined than with glass beads, Archimedes methods, or 3-D laser scanning (Britt and Consolmagno 2003;Li et al 2012).…”

The Kumtag 016 L5 strewn field, Xinjiang Province, China

“…Nine chips (2.71–5.04 g) free of weathering crust were prepared to determine the bulk density, the grain density, and the porosity at the Institute of Geochemistry, Chinese Academy of Sciences, performed using a Quantachrome Ultrapyc 1300e idea gas pycnometer, following the pycnometer‐balloon vacuum packing method described by Li et al. (). With this method, the precision of bulk density, grain density, and porosity are better than 0.6%, 0.03%, and 0.6%, respectively.…”

Petrology, mineralogy, porosity, and cosmic‐ray exposure history of Huaxi ordinary chondrite

“…Four fragments of Huaxi with masses of 2.29, 3.82, 2.84, and 3.26 g were used for the determination of densities and porosities with a Micro‐ultrapyc 1200e ideal gas pycnometer and applying the method developed by Li et al. (). The light noble gases were measured on two small fragments with masses of 55.62 and 57.09 mg.…”