Natural stone is required for maintenance and repair of historically, archaeologically and culturally important structures to prevent deterioration due to weathering and use. Those that have national or World Heritage significance are historically and culturally important. Sometimes, severely damaged buildings may require extensive or complete restoration. The choice of stone should be appropriate in physical and aesthetic terms, ideally from the original source. Researchers, architects, those who specify contracts and other stakeholders need reliable information, but access to, and awareness of, important sources such as manuscripts, publications and collections of samples is often limited. Easier access to information is needed when planning and commissioning works that require the replacement of stone. Making important information more widely available and promoting awareness of the need to maintain adequate supplies of natural stone of suitable quality is a task for both national and international organizations including the Heritage Stone Task Group of IUGS and IAEG. This paper provides some illustrative examples and pointers towards some recent major publications, as well as describing current Heritage Stone Resource and European Union initiatives, all the while requesting further participation from colleagues in this field.

B. J. Cooper, B.R. Marker, D. Pereira and B. Schouenborg. Episodes 2013;36:8-10. https://doi.org/10.18814/epiiugs/2013/v36i1/002

Conservation strategies to reduce the degradation of stone caused by the action of water are focusing on increasing the hydrophobicity of the surface by imitating existing solutions in nature (lotus leafs and others). These are mainly based on the existence of hierarchical roughness with micro- and nanoscale structures. In the case of marble, research has focused on protective coatings that sometimes are dangerous for the health and the environment, and with undesirable effects such as color changes or reduction of water vapor permeability of the stone. Laser texturing, however, is an environmentally friendly technique, because no chemicals or toxic waste are added and, moreover, it can process nearly all types of materials. It has been used to change the surface texture of metals and other materials on a micro or even nanometric scale, to meet a specific functional requirement, such as hydrophobicity. The objective of this work was to analyze the feasibility of this technique to provide hydrophobic properties to a marble surface without appreciable changes in its appearance. Therefore, an analysis of the irradiation parameters with ultra-short-pulse laser was performed. Preliminary results demonstrate the ability of this technique to provide hydrophobic character the marble (contact angles well above 90 ${}^{\circ }$ ). Besides, the analysis of the treated surfaces in terms of roughness, color and gloss indicates that changes in the appearance of the surface are minimal when properly selecting the process parameters.

Dolores Pereira. Episodes 2012;35:478-80. https://doi.org/10.18814/epiiugs/2012/v35i4/003

Serpentinites are used in both exterior and interior locations, but not all serpentinites are equal: they vary in physical-mechanical behavior and are not all suitable for similar uses. The serpentinites most commonly used worldwide come from India, Pakistan or Egypt. Spain has traditionally quarried two ultramafic massifs, one in Galicia (Verde Pirineos) and one in Andalucía (Verde Macael). Some of these quarries were small family-run businesses. In both cases, these rocks are commercially available as “green marble.” These serpentinites commonly have a high degree of carbonation, but the process does not always take place with the same intensity. Carbonate can act as a cementing agent of the other phases, increasing the mechanical strength parameters. As a result, an improvement in the strength conditions is achieved, but a misinterpretation of the suitability of the rock may occur because a perception among users that “green marble” is similar to geologically defined marble. This may lead to inappropriate applications as an ornamental stone. At a time of economic crisis in Europe, the natural stone sector is encouraged to invest in research to identify the best quality products that can compete profitably with those currently being imported from other countries. This paper provides a comparison of properties of the Verde Macael serpentinite with a true marble in the hope of contributing to improving the natural stone industrial sector.