This article appeared in the Summer 1967 (Issue #8) edition of the Kent Archaeological Review.
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Exploitation of Cement Stones and Copperas, North-east Kent.
The London Clay cliffs of North-East Kent contain two substances which played a part in industry a century or so ago; they were exploited by the coastwise inhabitants when conditions made the usual fishing impracticable. CEMENT STONES and COPPERAS were removed in great quantities which resulted from (and contributed to) the erosion of the cliffs. Collection (of the materials) was carried out on a family basis, like hop-picking, with everyone picking up, and filling baskets, from which a boat-load was accumulated, and taken away for processing.
- Cement Stones. The "septaria" of argillaceous limestone which occur in the clay were usable in two ways; first as a natural building stone, seen for instance in foundations and walls on Roman sites and in local churches, and secondly (after 1794) as cement, produced by burning and crushing, a process invented by James Parker of Northfleet and employed until the introduction of Portland cement after 1825. Parker called his product "Roman Cement", but it was not so used by the Romans. Tons of the nodules were carted away in the early 19th century, and (when the natural accumulation on the beaches from Herne Bay to Sheppey and on the Essex coast had been cleared,) the cliffs were dug away in search of more.
- Copperas or pyrites, an iron sulphide appearing in the debris of the cliffs, in small sausage-shaped nodules with a metallic appearance, was also collected for centuries in vast quantities, and removed to works at Whitstable and Queenborough, where a lengthy process was applied, which produced sulphuric acid and various grades of green iron sulphate, used in pharmacy, dyeing and other activities, including sheep-dipping for scab (Again, great damage to the cliffs resulted), until other method of making the acid were developed. A good deal of the documentary history of the Whitstable "copperas houses" is known, and the site of some of the pans in which the "ore" was spread out to oxidise (and mix with rain water to form an acid solution) was identified north of the UDC offices in 1947 (see Arch. Cant. LXX, 1957).