Analysis of systematic error in "bead method" measurements of meteorite bulk volume and density

    Authors

    R. J. Macke; D. T. Britt;G. J. Consolmagno

    Comments

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    Abbreviated Journal Title

    Planet Space Sci.

    Keywords

    Meteorite physical properties; Bulk density; Bead method; Porosity; INTERNAL STRUCTURE; POROSITY; CHONDRITES; Astronomy & Astrophysics

    Abstract

    The Archimedean glass bead method for determining meteorite bulk density has become widely applied. We used well characterized, zero-porosity quartz and topaz samples to determine the systematic error in the glass bead method to support bulk density measurements of meteorites for our ongoing meteorite survey. Systematic error varies according to bead size, container size and settling method, but in all cases is less than 3%, and generally less than 2%. While measurements using larger containers (above 150 cm(3)) exhibit no discernible systematic error but much reduced precision, higher precision measurements with smaller containers do exhibit systematic error. For a 77 cm(3) container using 40-80 mu m diameter beads, the systematic error is effectively eliminated within measurement uncertainties when a "secured shake" settling method is employed in which the container is held securely to the shake platform during a 5 s period of vigorous shaking. For larger 700-800 mu m diameter beads using the same method, bulk volumes are uniformly overestimated by 2%. Other settling methods exhibit sample-volume-dependent biases. For all methods, reliability of measurement is severely reduced for samples below similar to 5 cm(3) (10-15 g for typical meteorites), providing a lower-limit selection criterion for measurement of meteoritical samples. (C) 2009 Elsevier Ltd. All rights reserved.

    Journal Title

    Planetary and Space Science

    Volume

    58

    Issue/Number

    3

    Publication Date

    1-1-2010

    Document Type

    Article

    Language

    English

    First Page

    421

    Last Page

    426

    WOS Identifier

    WOS:000275041000007

    ISSN

    0032-0633

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