Diamonds and semi-precious gems, mineral resources, Northern Ireland

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Mitchell, W I (ed.). 2004. The geology of Northern Ireland-our natural foundation. Geological Survey of Northern Ireland, Belfast.

J W Arthurs and G Earls

Diamonds and semi-precious gems

The Brookeborough diamond, now set in Irish gold. (© Lord Brookeborough). (Photograph reproduced with the kind permission of the Trustees of the National Museums and Galleries of Northern Ireland). (P948057)

No diamonds or kimberlite intrusions (the most common host rock of diamonds) have been unequivocally shown to exist in Ireland. However, there are intriguing indications that diamondiferous intrusions could be discovered in Northern Ireland.

In spite of the Brookeborough Diamond (P948057), reportedly found in the Colebrooke River, Co. Fermanagh in 1816, no serious attempts were made at diamond exploration until 1996, when an exploration company carried out a programme of heavy mineral sampling in stream sediments in Counties Fermanagh and Tyrone. Although no diamonds were found, they reported that some samples contained an assemblage of grains of garnet, chromite and ilmenite possibly derived from kimberlitic source rocks.

A range of semi-precious stones is known from various localities in Northern Ireland, although none are of gem quality. Amber has been found in the Lough Neagh Group [1]. Beryl and rock crystal have long been known in drusy cavities in granites of the Mourne Mountains (Chapter 15). Tourmaline is widely scattered in Dalradian schists in the south Sperrin Mountains of Co. Tyrone.


  1. Shukla, B. 1989. Petrological, geochemical and palaeontological studies of the Lough Neagh Group. Unpublished PhD thesis, Queens University of Belfast, Northern Ireland.