1.1 This guide outlines procedures for the petrographic examination of samples representative of materials proposed for use as aggregates in cementitious mixtures or as raw materials for use in production of such aggregates. This guide is based on Ref (1). 1.2 This guide outlines the extent to which petrographic techniques should be used, the selection of properties that should be looked for, and the manner in which such techniques may be employed in the examination of samples of aggregates for concrete. 1.3 The rock and mineral names given in Descriptive Nomenclature C 294 should be used, insofar as they are appropriate, in reports prepared in accordance with this guide. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only. 1.5 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.