Talk:Elvan

Elvan and blue elvan
The article as it stands is a little confused. Elvans are "felsitic igneous rocks similar to granites in composition, but typically much finer-grained. They occur in association with the granite intrusions usually as dykes varying from a few centimetres to tens of metres in thickness." and include Pentewan stone, while the Blue elvans are a west Cornwall miners' term for Greenstones "a convenient name for a variety of basic (low silica content) dark coloured, intrusive igneous rocks, that have a variety of mineralogies, and are often referred to as dolerites or diabases in the geological literature (e.g. Floyd et al, 1993). Greenstones contain significant amounts of dark ferromagnesian minerals, and consequently are often very dark green or dark blue, near blackish, in colour.", such as Cataclews and Polyphant. The quotes are from the English Heritage "Cornwall Building Stone Atlas", pdf available from the British Geological Survey at this link.

I shall have a bash at improving the article to clear up this confusion, and also expand it a bit, in the next few days, but if anyone has any other useful sources which could be used in this then please do pitch in! DuncanHill (talk) 15:39, 27 January 2017 (UTC)