NGT35-10
1955
On the sulphides of the alum shale in Oslo.
35
117-120

The alum shale gives difficulties to building constructions in Oslo, both by heaving and by chemical attack on the concrete; a microscope study shows it to carry both pyrite and what is supposed to be pyrrhotite as minute grains. The attacking solutions are considered to be derived from the supposed pyrrhotite, formed during the Caledonian folding of the shale.