Firestone

A hard, siliceous building stone from the Upper Greensand of the North Downs, used for construction and for lining fireplaces and kilns.

Historical usage

Firestone and its softer companion stone Hearthstone are both varieties of Reigate Stone, quarried underground from the Upper Greensand along a narrow strip of the North Downs between Godstone and Brockham in east Surrey — the same beds worked at Merstham. Firestone's harder, siliceous character suited it to ordinary building work and to lining fireplaces, kilns and furnaces, where its heat resistance was valued long after its use as an ordinary building stone had declined.

How it worked

Mined underground in lumps using hammers and wedges, following the natural joints in the rock, in passages that were typically rough rather than carefully dressed, since the finish did not matter for firestone's principal industrial uses.

Why it was used

Firestone's hardness and resistance to heat made it useful as an ordinary building stone and, once the wider building trade moved to other materials, kept a market as a refractory lining material for fireplaces, kilns and furnaces.

Risks & limitations

As transport improved through the 18th and 19th centuries and other building stones became more easily available, firestone lost most of its market for ordinary construction, surviving mainly in its narrower refractory role.

Regional variation

A Surrey and Kent term for this particular Upper Greensand building stone; elsewhere in Britain comparable stone is known by different local names.

Mines associated with this term

Included only where MineArchive's own research gives a reasonable evidential basis — not every mine where this might plausibly apply.

• Merstham Chalk Mines — Surrey (well documented example)
  Named 5 times in this record, first in the summary: “…at Merstham for perhaps a thousand years, supplying the calcareous 'firestone' building stone used at Westminster, Windsor Castle and Old St…”
• Reigate Caves — Surrey (well documented example)
  Named in this record’s geology: “…stone industry worked a different bed entirely: Reigate stone, or firestone, comes from the Upper Greensand along the foot of the North Downs,…”

Sources

1. (secondary) History of Merstham — Reigate and Redhill Society
2. (secondary) The Exploitation, Distribution and Use in Buildings of Reigate Stone pt1 — Croydon Caving Club

Record created: 27 August 2026 · Last researched: 27 August 2026