The mineralogical and chemical methods in investigations of decay of the Devonian black ‘marble’ from Debnik (Southern Poland)

Abstract

Optical microscopy, scanning electron microscopy with energy dispersive spectrometry, X-ray diffraction, infrared (IR) spectroscopy, Rock-Eval pyrolysis and gas chromatography combined with mass spectroscopy were used to examine deterioration of the black limestone from Dr near Cracow. Owing to its unique colour and good polishing properties the rock is called the 'D~bnik marble'. The samples were taken from various monuments and natural outcrops exposed to weathering. The material is a compact limestone whose black colour is caused by an admixture of bitumens or pyrite. Its horizontal layers are separated by discontinuities filled with clay minerals. Surface exfoliation is one of the damage signs and results in the formation of irregular or lensoidal fractures. The discontinuities provide an easy access for acid rain that in reaction with calcite produces gypsum.Crystallization of gypsum leads to alveolar weathering, cracking and chipping of the otherwise compact material. The presence of alveoles or surface exfoliation depends on the orientation of stone blocks. When they are cut along the discontinuities, destruction results in exfoliating and cracking. Perpendicular cutting gives rise to the formation of alveoles. The changes affect the original black colour of the stone surface that alters to grey or even white.

Black "marble" in the Polish architecture - characteristics and possibility of its provenance determination: the case of the Dębnik limestone

“…The effects of graying or whitening of the stone surface in the case of the Dębnik limestones are widely observed both in outcrops and architectonic artifacts (Kozłowski & Magiera 1989, Wilczyńska-Michalik 2004, Marszałek et al 2006, Marszałek 2007, Marszałek & Skowroński 2010. Superficial graying (or whitening) of the limestone exposed to a polluted, urban atmosphere is combined with deposition of anthropogenic particulates on the stone surfaces.…”

“…The elements cut out of the stones without sedimentary textures, i.e., the micritic limestones and the micritic limestones with fauna, are more resistant (Niemcewicz 2005, Marszałek 2007). …”

“…% TOC (total organic carbon) that corresponds to 4.4 wt. % TOC in the HCl-insoluble fraction; they exhibit the features of the type III kerogen, i.e., the kerogen derived from humic organic matter of probable algal and bacterial origin (Marszałek & Muszyński 2001, Marszałek 2007. The organic compounds represent a mixture of fatty acids, saturated and non-saturated n-alkanes C 16 -C 20 , aromatic hydrocarbons and polycyclic hydrocarbons (Marszałek 2007).…”

Deterioration of the black Drenov Grič limestone on historical monuments (Ljubljana, Slovenia)

“…Many inner and outdoor architectural elements and monuments, especially portals of houses and altars, were made of this limestone (Ramovš 2000). The extensive use of black limestones was also reported to be characteristic for the baroque period in other parts of European countries (Marinoni et al 2002;Zehnder 2006;Marinoni et al 2007;Marszałek 2007). However, when exposed to climatic influences, chromatic weathering and salt weathering are recognized as the main deterioration phenomena of these limestones.…”

“…Some fragments of fossils of bivalvia, gastropoda, algae, foraminifera, ostracods, and chorals are also found (Ramovš 2000). Black limestones are normally micritic limestones relatively rich in carbonaceous and bituminous matter, which is supposed to be responsible for their dark color (winkler 1997;Marinoni et al 2007;Marszałek 2007). As the limestone is dense, resulting in a good polishing effect, it was popularly considered as marble.…”