Weathering of Granite-Based Stone Cultural Heritage: A Multianalytical Review of Mineralogical Alteration, Microcracking, and Decay Patterns

Granite is a major lithology of stone-built cultural heritage across East Asia, the Iberian Peninsula, the Indian subcontinent, Egypt and Italy. Long regarded as durable, it nonetheless undergoes mineralogical, microstructural and macroscopic alteration through pathways that are mechanistically universal yet regionally distinctive in expression. This review synthesizes granite weathering within a multianalytical framework spanning mineralogy, microstructure, geochemistry, environmental drivers and conservation science. Mineral-specific reactions—feldspar hydrolysis, biotite oxidation coupled to clay-mineral genesis, iron-bearing transformations driving surface coloration, quartz-mediated thermal microcracking and accessory-mineral pathologies—are examined as coupled processes governing macroscopic decay. A suite of complementary analytical methods, including non-destructive, minimally invasive and laboratory-based techniques, delivers mechanistic and prognostic resolution unattainable by any single method. Two case settings—the tenth-century rock-carved Buddhas of Gyeongju Namsan and the urban granite of Jongmyo Shrine, Seoul—illustrate how integrated diagnostics resolve coupled decay on natural outcrops and how cumulative atmospheric exposure is recorded in monument-scale fabrics. Chemical weathering indices, environmental controls and conservation implications are unified into a single framework, and key gaps—standardization, time-resolved diagnostics, climate projection, multi-omics coupling, consolidant durability and machine learning—are articulated as a research agenda for granite heritage science.