Calcareous sinter

Deposits are characterised by low porosity and well-developed lamination, often forming crusts or sedimentary rock layers.

Pedley (1990)[3] suggests the term be abandoned in favour of tufa for ambient temperature deposits.

With deposits up to 30 centimetres (12 in) thick, the material was cut into vertical columns of polished brown rock with impressive layered patterns, which made it much in demand by cathedral builders across large parts of central Europe and beyond.

[4] In England it was used to provide polychromy, contrasting with the pale limestone favoured by Norman English Cathedrals.

[5] Such large-scale use as the cloisters around a cathedral quadrangle needed many hundreds of columns, which must have been supplied by a well-organised extraction and transport operation.