This data publication is part of the 'P³-Petrophysical Property Database' project, which has been developed within the EC funded project IMAGE (Integrated Methods for Advanced Geothermal Exploration, EU grant agreement No. 608553) and consists of a scientific paper, a full report on the database, the database as excel and .csv files and additional tables for a hierarchical classification of the petrography and stratigraphy of the investigated rock samples (see related references). This publication here provides a hierarchical interlinked petrographic classification according to standardized and internationally defined petrographic terms. The petrography or rock type classification scheme is structured based on a hierarchical subdivision with nine different ranks, where the rock description generally becomes more detailed with increasing rank of petrographic classification (based on the well database of the Geological Survey of Hessen, Germany: Hessisches Landesamt für Umwelt, Naturschutz, Umwelt und Geologie (HLNUG)). This hierarchical subdivision and the definitions of the petrographic terms are based on international conventions (e.g. Bates & Jackson 1987, Gillespie & Styles 1999, Robertson 1999, Hallsworth & Knox 1999, Bas & Streckeisen 1991, Schmid 1981, Fisher & Smith 1991). Furthermore, the classification corresponds to the subdivision provided by existing property data compilations such as e.g. Hantschel and Kauerauf (2009), Schön (2011), Rybach (1984) and Clauser and Huenges (1995). Petrographic classifications from rank 1 to rank 4 can usually be identified from macroscopic descriptions of well logs, cores and geological mapping. The petrographic classifications from rank 5 to rank 9 require additional information on the texture or grain size, the modal composition or the geochemistry etc., which can usually only be acquired by microscopic or comparable special investigations. Overall, the nine ranks cover a total of 1494 petrographic terms and thus goes well beyond other standardized catalogues (e.g. 'Simplified Lithology' in GeoSciML). The petrographic classification of a sample in P³ is based on the sample description within the original literature reference. A petrographic ID and a corresponding petrographic parental ID directly correlate the different classifications and their ranks.