How does bog oak form?

Oak trunks that fell or sank into a raised bog several thousand years ago are protected there from decay by the lack of oxygen. At the same time the humic acids contained in the bog act on the tannin in the oak timber and lead to a chemical blackening of the entire trunk. The resulting material is markedly harder than fresh oak, markedly darker in colour and readily polishable - an ideal jewellery substance for black mourning jewellery. Age determinations typically yield 2,000 to 7,000 years.

How does bog oak differ from Whitby jet?

Both materials are deep black and were used for mourning jewellery in the 19th century, but they differ in origin, hardness and working. Bog oak is subfossil oak timber - lighter, softer, more fibrous, with a recognisable wood grain; ideal for carved floral motifs (shamrock, harp, round towers). Whitby jet (see Whitby Jet) is a fossilised variety of coal - heavier, harder, without grain, with a high lustre after polishing. Bog oak had the lesser prestige and was regarded as a patriotic, vernacular material; Whitby jet was the high-priced standard material of the English mourning establishment.

Is bog oak still worked today?

Only to a very limited extent. In Ireland a few specialised craftspeople make pieces of jewellery from bog oak to order - partly from historically recovered material, partly from modern peat-cutting finds. Working it requires very careful drying over several months, since the water-rich fresh material would otherwise crack. Bog oak is today no longer a mass jewellery material but a collectors' and craft niche, often traded with a patriotic Irish context.

Bog Oak

Bog oak is oak timber preserved for thousands of years in raised bog, which turns deep black through interaction with humic acids and which in the 19th century became, above all in Ireland, a vernacular, inexpensive material for mourning jewellery - a patriotically charged counterpart to English Whitby jet.

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