Summary
Porcellanite or porcelanite, is a hard, dense rock somewhat similar in appearance to unglazed porcelain. It is often an impure variety of chert containing clay and calcareous matter.[1] Porcellanite has been found, for example, in Northern Ireland, Poland and the Czech Republic. Porcellanite is also commonly found in the Northern Territory of Australia. There, it comes in a variety of colours, primarily white, yellow, red and purple.
Tievebulliagh edit
At Tievebulliagh, Northern Ireland, porcellanite is a tough contact metamorphosed hornfels formed from a lateritic soil horizon within a basaltic intrusive/extrusive sequence. The rock is black to dark grey in colour. Tievebulliagh is the site of a Neolithic axe or stone tool quarry, and there is another quarry on Rathlin Island.[2] It is likely that roughouts or roughly-shaped prehistoric tools (celts) were chipped on site before transportation both within Ireland and over the Irish Sea to Britain.[citation needed] It is also likely that the final polish would have been performed near the site of use in cutting vegetation and trees.[citation needed] It was commonly polished on grooved blocks of hard sandstone.[citation needed]
References edit
- ^ The Editors of Encyclopædia Britannica (20 July 1998). "Porcellanite". Encyclopædia Britannica. Encyclopædia Britannica Inc. Retrieved 28 March 2017.
- ^ "Tievebulliagh". Geological Sites in Northern Ireland — Earth Science Conservation Review. Habitas — National Museums Northern Ireland. 3 May 2003. Retrieved 28 March 2017.