The petrography of the Giffnock sandstone from the interior of the Kelvingrove Art Gallery and Museum, Glasgow

John J. Hughes, Norman H. Tennent

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Samples of sandstone from the interior of the Art Gallery and Museum at Kelvingrove in Glasgow were characterised. The samples investigated comprised those cleaned using an EDTA/natural rubber latex poultice method during the 2004-6 refurbishment of the Gallery and uncleaned samples with an intact black soiling patina. This study was undertaken in order to provide a petrographic explanation of the stone coloration and the efficacy of the cleaning methodology. The stone is a medium grained, well sorted quartz arenite, containing mono-crystalline quartz, extensively dissolved microcline feldspars, muscovite micas, opaque oxide minerals and rare accessories such as zircon, tourmaline, apatite and rutile. Sub-angular to sub-rounded framework grains exhibit pressure solution contacts and occasional overgrowths. Secondary minerals are ankerite cements, kaolinite clays and iron oxyhydroxides. The stone exhibits a warm honey colour or a more grey tone, related to secondary iron oxide mineral content. Relationships between iron oxyhydroxide, ankerite and kaolinite suggest a complex diagenetic history for the stone, in addition to an overprint of mineral growth related to post quarrying exposure. We tentatively propose two morphologies for ankerite. In euhedral masses, a compositional zoning is evident as a late Fe and Mn enrichment and Mg depletion. The honey-coloured surface patina common on many of the cleaned blocks in the Gallery is generally present in a zone up to 5 mm from the exterior surface. Interstitial masses of iron oxyhydroxide can be seen increasing in occurrence towards the exterior of the stone in the honey-coloured samples. There is evidence for the progressive replacement of ankerite with the iron oxyhydroxide phases. In some, the brown iron oxyhydroxide coloration is present throughout the thickness of the sample, but these samples exhibit a greyish surface colour, with a depleted Fe zone on the exterior, and do not contain any carbonate cement. Samples with a honey-coloured surface contain abundant ankerite cement but less interstitial iron oxyhydroxide, except near the surface where replacement of carbonate becomes common. Uncleaned samples have a thin black, opaque surface layer up to 100 µm thick, whose elemental composition includes Si, Al, S and Fe. In one sample, Ba is also present in small barite grains. Gypsum is present in the soiling layer, but full characterisation of the blackened surface has not been undertaken.
Original languageEnglish
Title of host publication11th International Congress on Deterioration and Conservation of Stone. 15-20 september 2008, Torun, Poland. Proceedings
PublisherNicolaus Copernicus University Press
Pages651-660
Number of pages10
Volume1
Edition1
ISBN (Electronic)978-8323122364
ISBN (Print)8323122369
Publication statusPublished - 2008
Event11th International Congress on Deterioration and Conservation of Stone - Torun, Poland
Duration: 15 Sep 200820 Sep 2008

Conference

Conference11th International Congress on Deterioration and Conservation of Stone
CountryPoland
CityTorun
Period15/09/0820/09/08

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  • Activities

    • 2 Types of External academic engagement - Contribution to the work of national or international committees and working groups
    • 1 Publication peer-review

    14th International Congress on the Deterioration and Conservation of Stone (Event)

    John Hughes (Peer reviewer)

    24 Feb 2020

    Activity: Publication peer-review and editorial workPublication peer-review

    Permanent Scientific Committee of the International Stone Congresses

    John Hughes (Member)

    20162028

    Activity: OtherTypes of External academic engagement - Contribution to the work of national or international committees and working groups

    ICOMOS ISCS - International Scientific Committee for Stone. Expert Member

    John Hughes (Member)

    2016 → …

    Activity: OtherTypes of External academic engagement - Contribution to the work of national or international committees and working groups

    Cite this

    Hughes, J. J., & Tennent, N. H. (2008). The petrography of the Giffnock sandstone from the interior of the Kelvingrove Art Gallery and Museum, Glasgow. In 11th International Congress on Deterioration and Conservation of Stone. 15-20 september 2008, Torun, Poland. Proceedings (1 ed., Vol. 1, pp. 651-660). Nicolaus Copernicus University Press.