Stone in Archaeology Database


Kentish Rag

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Local Name(s): Kentish Rag. Example of Kentish Rag
Stone Group: Sedimentary
Stone Type: Limestone
Geology:
Era:   Mesozoic
Period:   Cretaceous
Epoch:   Lower
Geological Sub-Divisons:

Lower Greensand Group, Hythe Formation.

General Colour Description:

Two layers are important: the Ragstone which is a bluish/grey colour and the Hassock which is a grey colour.

Hand Specimen Description:

The ragstone is a hard, coarse grained, sandy limestone comprising rounded, detrital grains of quartz and glauconite, cemented by calcite (85% of the rock is calcium carbonate). It occurs in layers from 10 - 90 cm thick. This is interbedded with layers of hassock, a loamy, calcareous, glauconitic sand (Worssam & Tatton-Brown 1993: 93-4).

Petrographic Description:

The proportion of the minerals may differ considerably and the lithology varies considerably along its outcrop. There is every gradation from a sandstone with abundant calcerous cement (mainly of organic origin) to a shelly limestone with scattered sand grains. A predominance of silica indicates a sandstone and in fact the amount of silica of some beds rises to the level where these beds are indeed regarded as sandstones and not limestones.

General Comments:

This stone can be mistaken for Reigate stone, however Kentish Rag is not micaceous and is particularly calcareous with rounded rather than amorphous grains of quartz.

Stone Identifiers: Calcareous,  Glauconitic.
Reacts dilute to HCl? Yes