Fig. 7From: Conservation issues and chemical study of the causes of alteration of a part of the Stave Church in Hopperstad (Norway)SEM micrograph of the bird dropping sample (a), from the floor (b, c), crossbar (d), the southern exterior door (e) and the portal above the southern entrance (f). The flake-like structures are marked in b and the triangular crystals are marked in c. A cluster that could be a mixture of organic and inorganic particles is marked in dBack to article page