The simple oxide ore of tin, cassiterite (SnO2),
accounts for virtually all the tin that has ever been recovered.
It is noted for its high specific gravity (its heaviness),
approximately three times the weight of a comparablysized piece of
the granite with which it is normally associated. Where tin lodes
have reached the surface, weathering and erosion over millions of
years have broken up the vein structure and released the
cassiterite which is stable and durable and resists rapid
breakdown. It tends to lie on the surface as coarse eluvial
material, often mixed with quartz. When washed into river valleys,
it forms concentrated alluvial deposits of dark coloured pebbles
Tin smelting in Cornwall was, on the
whole, a more capital-intensive and lucrative business than mining
and was controlled by a ‘ring’ or cartel of a few families. Money
was often advanced to mines or miners, to be re-paid in tin. For
the Bolitho family of Penzance this practice led to them becoming
bankers. Thomas and William Bolitho founded The Mounts Bay
Commercial Bank in 1807 in the count-house of their Chyandour
Smelting House. The Consolidated Bank of Cornwall was taken over
by Barclays Bank in 1905. The principal Cornish families engaged
in tin smelting were the Daubuz, the Williams, the Harveys and the
The ownership of smelting houses, and of the smelting companies
themselves, changed frequently throughout the nineteenth century
as industrial families changed their alliances and strategies. A
landmark technical improvement in Cornish tin smelting came in
1702. This was the introduction of the reverberatory furnace at
Newham (Truro). This used coal instead of charcoal and the charge
of tin was no longer mixed with (and contaminated by) the fuel but
was reduced by the application of heat alone.
|By the nineteenth
century, most tin smelting was conducted in reverberatory
furnaces, although the larger and more important blowing houses
remained until the mid century.Tin smelters within the region were
initially concentrated close to the Stannary Towns and navigable
rivers or harbours. Those in Cornwall tended to migrate from east
to west as production shifted from tin-streaming to deep
lode-mining. Most of these early important tin smelters were
concentrated in Penzance, Hayle, Truro and the St Austell area.
Later, when rail transport had developed (and coinage had been
abolished) Redruth became an important centre for tin smelting.
Uses of tin
For centuries, Cornish tin production was destined
for The Worshipful Company of London Pewterers and gave rise to
important medieval ports such as Truro. Coins were also minted:
tin halfpennies and farthings were introduced by King James II
(reigned 1685-1688). In all £10,000 worth of tin was purchased,
and £65,000 worth of coins issued. Bronze (an alloy of copper and
tin), once used in the production of cannon (before the
development of large reliable iron castings) was also essential
for precision instruments.
In 1789 a major new market was found for Cornish
tin. The East India Company, which had a monopoly on all official
“British” trade with China, began to buy around two thousand tons
a year. This was consumed as tinfoil in religious ceremonies.
Around half of this demand was met by Cornwall.
Tin-plated cans to preserve and transport food
were invented by Peter Durand in 1810. During the early decades of
the nineteenth century major growth in the tin-plate industry
created a new and vibrant demand. Solder was an essential part of
that industry and it also became a vital requirement of the
electrical industry in the second half of the nineteenth century.