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<p>The Pelequén Pink Stone, quarried for over 150 years and central to the cultural and economic identity of Pelequén, Chile, is hosted within an ignimbrite deposit of the Las Chilcas Formation (Lower Cretaceous, ~ 138&#xa0;Ma). Here we investigate its geological origin, petrographic characteristics, geomechanical behavior, and the nature of discontinuities locally referred to as “hairs.” Petrographic analysis of the “peach blossom” variety reveals a mineral assemblage dominated by albite, sanidine, and quartz, with albite occurring as resorbed phenocrysts and sanidine and quartz in the groundmass, alongside pumice and lithic fragments. The characteristic pink coloration is attributed to the abundance of feldspar phases. Mechanical testing (uniaxial compressive strength, indirect tensile strength, and point load tests) indicates moderate strength (UCS ≈ 33&#xa0;MPa; TS ≈ 2.5&#xa0;MPa), with porosity ranging from 13% to 28% and exerting a primary control on strength through a negative linear relationship. Field observations highlight vertical variability in porosity linked to ignimbrite emplacement, the presence of oriented pumice fragments, and joint and fracture systems of tectonic origin. However, laboratory results do not provide conclusive evidence that “hairs” or pumice fragments significantly reduce strength or control failure mechanisms. These findings suggest that the mechanical behavior of the stone at laboratory scale is primarily governed by porosity rather than discrete discontinuities, and that its variability is inherently controlled by depositional and post-depositional geological processes. Improved geological characterization of porosity distribution and structural features is therefore essential for optimizing extraction and ensuring material quality and safety. Given its distinctive geological properties and strong cultural significance, we propose the Pelequén quarry as a candidate Geosite, highlighting its relevance to Cretaceous volcanism in central Chile and its potential for geotourism.</p>

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The Strength of Tradition: Physical and Mechanical Properties of Pelequén’s “Peach Blossom” Pink Tuff, Chile

  • 期刊论文

  • 发表日期：

    2026年6月30日

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  • Franco Robbiano,
  • Laura Becerril,
  • Domingo Jullian,
  • Luis Felipe Orellana

摘要

The Pelequén Pink Stone, quarried for over 150 years and central to the cultural and economic identity of Pelequén, Chile, is hosted within an ignimbrite deposit of the Las Chilcas Formation (Lower Cretaceous, ~ 138 Ma). Here we investigate its geological origin, petrographic characteristics, geomechanical behavior, and the nature of discontinuities locally referred to as “hairs.” Petrographic analysis of the “peach blossom” variety reveals a mineral assemblage dominated by albite, sanidine, and quartz, with albite occurring as resorbed phenocrysts and sanidine and quartz in the groundmass, alongside pumice and lithic fragments. The characteristic pink coloration is attributed to the abundance of feldspar phases. Mechanical testing (uniaxial compressive strength, indirect tensile strength, and point load tests) indicates moderate strength (UCS ≈ 33 MPa; TS ≈ 2.5 MPa), with porosity ranging from 13% to 28% and exerting a primary control on strength through a negative linear relationship. Field observations highlight vertical variability in porosity linked to ignimbrite emplacement, the presence of oriented pumice fragments, and joint and fracture systems of tectonic origin. However, laboratory results do not provide conclusive evidence that “hairs” or pumice fragments significantly reduce strength or control failure mechanisms. These findings suggest that the mechanical behavior of the stone at laboratory scale is primarily governed by porosity rather than discrete discontinuities, and that its variability is inherently controlled by depositional and post-depositional geological processes. Improved geological characterization of porosity distribution and structural features is therefore essential for optimizing extraction and ensuring material quality and safety. Given its distinctive geological properties and strong cultural significance, we propose the Pelequén quarry as a candidate Geosite, highlighting its relevance to Cretaceous volcanism in central Chile and its potential for geotourism.