ASTM D7708-14

5.1 The mean reflectance of the vitrinite maceral in sedimentary rocks as determined by this test method is used as an indicator of thermal maturity, that is, the progressive geochemical alteration of dispersed organic material experienced during diagenesis, catagenesis, and metagenesis. In the case of hydrocarbon source rocks, three major categories of thermal maturity are defined by vitrinite reflectance: immature (R_{1.1 This test method covers the microscopical determination of the reflectance measured in oil of polished surfaces of vitrinite dispersed in sedimentary rocks. This test method can also be used to determine the reflectance of macerals other than vitrinite dispersed in sedimentary rocks.}

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.