Great Tew Ironstone

Great Tew Ironstone [The MarlstoneRockbed] has a distinctive deep orangebrowncolour with occasional patches of white mineralisation/marbleing and is commonly found throughout the counties of North Oxfordshire, Northamptonshire through to Rutland. Overall the stone is fine grained with some particles having a deep iron-rich colour with others being paler.

Petrographic Description and Mineral Examination

In thin section the stone had a high content of rounded to angular grainules ranging in colour from dark iron-brown to pale orange. Sometimes the grains were
oolitic, with seeds and rims of different composition/texture. These grains were generally well-compacted and often grainsupported. Also present were broken up fossil fragments which appeared to include bryozoan, bivalves, echinoid and crinoid pieces.

A partial carbonate cement is visible throughout the section, with the distribution of this being rather variable. Patches showing a well-developed cement are those areas of the hand specimen appearing white and more resistant. There was also evidence of a fine siliceous/clay matrix in some areas of the section. Based on the mineralogy identified in thin section
and the texture seen in hand specimen, the stone has been given the classification of Ferruginous limestone.

BRE Test Data

*All comprehensive British and European Standards test data and declaration of performance for CE marking
application are available on request.