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Discusses the treatment of sphericity and roundness data of quartz grains of clastic sediments. Non-normal distribution of sphericity and roundness data of quartz grains of sieve fractions; Results of laboratory experiments on sampling quartz grains; Frequency of sphericity and roundness data.

The observed size in the thin-section is less than the true train sizes of the clastic rock as the thin-section plane does not necessarily pass through the centre of gravity of the grains. Correction factors based on probability theory give corrected arithmetic moments of the size distribution in the elastic rock from the observed arithmetic moments of the size distribution in the thin-section. The corrected arithmetic moments so obtained are transformed to their equivalent corrected phi moments which are useful to generate the unknown size distribution of the clastic rock by the help of Edgeworth's series. [ABSTRACT FROM AUTHOR]

The cumulative frequencies are obtained from the phi size-distribution moments (duly corrected for random sectioning) based on either weight or number frequency thin-section size data by the use of Gram-Charlier approximation. From the cumulative frequency distribution the various size-distribution statistics can be easily obtained and these statistics are useful for purposes of comparison, correlation, and interpretation of size data. [ABSTRACT FROM AUTHOR]

The weight-frequency size distribution is generally accepted to be log-normal (phi-normal) for sandstones, but the nature of number-frequency distribution of particles in sandstones is largely unknown. This paper develops the theory of correction procedure for the observed weight-frequency moments obtained by thin-section analysis of sandstones (and clastic sediments in general) which was not available so far. [ABSTRACT FROM AUTHOR]