COMPARISON OF THE METHODS OF ROCK-MICROSCOPIC GRAIN-SIZE DETERMINATION AND QUANTITATIVE-ANALYSIS

This study is a methodological investigation of the textural constitue nts of one- and multicomponent magmatic, sedimentary, and metamorphic rocks as well as artificially cemented composites (concrete, ceramics, etc.) in view of both quantity and grain-size distribution. After the theoretical comparison of the known procedures available (e.g., point counting, measurement along reference lines, planimetry, etc.) the mo st convenient measurement technique is selected, complemented, then ch aracterized. Most convenient for the dual purpose, with respect to eff iciency and standard deviation, is the simple measurement with a scale d cross hairs eyepiece along a reference line. The basic data obtained in this way can be presented both in tables and diagrams. Irt the are a under the cumulative curve demonstrable in the semilogarithmic grain site-frequency coordinate system, well known in sedimentology, size-d istribution of the constituents can be presented. On the grounds of th e individual character of the exact data described, assumptions on the properties, degree of homogeneity, and origin of the material can be drawn. The optimal procedure selected is suitable for computer process ing. The texture of the rocks can be characterized with the variable a ccuracy desired, any unnecessary excess work, and oversize measurement can be avoided. At the same time, an opportunity is opened to check t he reliability of earlier measurements performed with different method s or on limited amounts of material (e.g., drill core).