The occurrence of rare minerals on decayed medieval Scottish building stone colonized by biological growths

Abstract

During the course of a study of biodeterioration at Hermitage Castle in the Scottish Borders various rare minerals: monohydrocalcite, nesquehonite and dypingite were found in association with the biological growths. Monohydrocalcite was found particularly in association with a green alga Trentepohlia aurea. A brief review of previous publications concerning these minerals is given and the theory put forward with regard to the possible origin of the monohydrocalcite as a biogenic by product.