Bampfylde, 1854: what happens when you believe your best assay
Victorian Devon had rich gold assays, imported American technology and serious money. The bulk processing recovered nothing at all. It is the most useful failure in the county's mining history.
Every optimistic story about gold in Devon eventually runs into North Molton, and it is worth understanding exactly how that happened, because the failure mode is not a nineteenth-century one. It is a permanent one.
The setup
Gold in the copper deposits at Bampfylde Mine, near North Molton on the southern fringe of Exmoor, had been known since at least the late 18th century. Polwhele, quoting Chapple, records gold found in a rich copper mine in the parish. The mine had long carried the telling name of the “king’s mine”, a reference to the Crown’s prerogative claim over precious metals, which tells you people took the gold seriously enough to worry about who owned it.
In the 1840s the Prince Albert Mining Company was formed, and one of its adventurers approached the Crown for the right to work gold specifically. A parallel application to work gold “at South Moulton” ran from 1843 to 1849. So far this is ordinary Victorian mineral speculation.
Then California happened in 1848, and Australia in 1851, and the temperature changed completely.
The technology
What is striking is that they did this properly. This was not two men with a shovel.
In 1854 a Perkes machine was installed at the Britannia Mine, and a Berdan machine at the nearby Bampfylde Mine, then known as the Poltimore. These were state-of-the-art amalgamation devices: heavy iron rollers or spheres rotating inside an iron pan, crushing and grinding ore while mercury scavenged the liberated gold. The Berdan in particular was trialled extensively across the South West in this period.
The technology was not the problem. Berdan machines and their descendants went on to work perfectly well in the Welsh goldfields; a pair of Britten pans from the Bedd-y-coedwr mine survives at Coed y Brenin in Merioneth.
The result
From Peter Claughton’s assessment for the mining history community, the outcome of bulk treatment at both mines:
the rich gold assays had been highlighted and poor returns ignored, and the bulk treatment of ores from both mines failed to recover any gold
Not “recovered less than hoped”. Not “was marginally uneconomic”. No gold.
The failure mode
That sentence contains the whole lesson, and it is worth separating into its two halves.
Selection bias in the assays. Somebody sampled the ore, got a range of results, and the good ones went into the prospectus. This is not fraud, necessarily; it is what enthusiasm does to a dataset when there is money at stake. Gossan, the weathered iron-stained outcrop that Victorian prospectors loved to assay, is particularly treacherous: secondary enrichment can concentrate gold near surface into values that vanish the moment you go deeper or process in bulk.
Look at the Dartmoor numbers from the same era with this in mind:
| Site | Reported grade |
|---|---|
| Drewsteignton company, 1855 | ½ oz per ton of gossan |
| Holne Chase Mine | 7.5 g per tonne |
| Tavistock mine, 1865 | 14 g per tonne |
Every one of those would be a viable grade today. Every one of them produced nothing. They are the same phenomenon as North Molton, recorded at sites that never got as far as buying a Berdan machine.
Grade collapses under bulk. A hand specimen can be spectacular and mean nothing. An assay is a measurement of the rock you chose to assay. What matters is the average grade of everything you must move, and in Devon that average has always been approximately zero.
Why this still applies
I keep returning to this because the pattern recurs in modern amateur prospecting almost unchanged. Somebody finds colour in a pan, extrapolates from the best pan of the day, and concludes there is real gold in the stream. The BGS did the disciplined version of this across 450 sites in the South Hams and found that 44 of them exceeded 0.5 ppm, which is a genuinely useful result precisely because they published the 406 that did not.
The honest question is never “what did the best sample give?” It is “what is the average, and how much material would I have to move?”
For Devon, the answer to that has been the same since 1854. Which is not a reason to stay home: panning a stream you have permission to work is a fine way to spend a day, and finding a flake of palladium-bearing dendritic gold in a Devon combe is a genuinely remarkable thing to hold. It is only a reason not to mistake it for a deposit.
More on the documentary history on the history page.