Petit Granit: A Belgian limestone used in heritage, construction and sculpture

Abstract

Petit Granit is a Carboniferous grey-bluish crinoidal limestone that becomes shiny black when polished. The rock is known under several other names including Pierre bleue (Blue stone), but it should not be confused with other natural stones having a similar commercial name, which are superficially similar limestones. It consists of around 96% microcrystalline calcite and a high proportion of fossils, mainly crinoids. In addition some dolomite, quartz, pyrite, marcasite and fluorite are present. Around fifteen quarries are currently active, employing almost one thousand people and thus is an important part of the natural stone economy in Belgium. Petit Granit has an Appellation d'Origine Locale (Local Appellation of Origin) designation since 1999. It has been extracted in several regions of southern Belgium since the Middle Ages. The stone characterizes many facades of the urban architecture of Brussels and other Belgian cities, and since the second half of the 19 th century it has been used in various countries elsewhere in Europe and overseas. Its high density and uniformity mean that it takes an excellent polish and thus has versatile use as a dimension stone. Petit Granit has also been used widely in sculpture and architecture by several well known artists. However, deterioration has been observed when it has been used for exterior purposes, and appropriate measures need to be taken to prevent this. This stone can be considered as a possible candidate for Global Heritage Stone Resource nomination in Europe for its prominence and value both in construction and artistic uses.