Elvan is a name used in

Cornwall Cornwall (; or ) is a Ceremonial counties of England, ceremonial county in South West England. It is also one of the Celtic nations and the homeland of the Cornish people. The county is bordered by the Atlantic Ocean to the north and west, ...

and

Devon Devon ( ; historically also known as Devonshire , ) is a ceremonial county in South West England. It is bordered by the Bristol Channel to the north, Somerset and Dorset to the east, the English Channel to the south, and Cornwall to the west ...

for the native varieties of

quartz-porphyry Quartz-porphyry, in layman's terms, is a type of volcanic (igneous) rock containing large porphyritic crystals of quartz. These rocks are classified as ''hemi-crystalline acid rocks''. Structure The quartz crystals exist in a fine-grained matrix ...

. They are dispersed irregularly in the

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

series of rocks and some of them make very fine building stones (e.g. Pentewan stone, Polyphant stone and Catacleuse stone). Greenstone is another name for this stone and it is often used for parts of buildings such as doorways so they can be finely carved. Most of the elvan quarries are now disused. Others are quarried in bulk for aggregates commonly used for road-building. More precisely there are two types of rock in this category: one is "white elvan" and the other is "blue elvan". "White elvans" are a group of fine-grained, acid igneous rocks, while "blue elvans" or "greenstones" are various unusual basic igneous rocks. "White elvan" comes from various different locations and is often known as

Pentewan Pentewan (, meaning ''foot of the radiant stream'') is a coastal village and former port in south Cornwall, England, United Kingdom. It is situated at south of St Austell at the mouth of the St Austell River. Pentewan is in the civil pari ...

stone (or by other names based on the location). Some older descriptions of building stones have called "white elvans"

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

, e.g. in studies of Lemon Street, Truro.

Archaeology

Approximately 400 prehistoric stone axes, known as Group 1 axes and made from greenstone, have been found all over Britain, which from

petrological Petrology () is the branch of geology that studies rocks, their mineralogy, composition, texture, structure and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous an ...

analysis appear to come from west Cornwall.Markham, M. & Floyd, P. A. (1998) "Geochemical Fingerprinting of West Cornish Greenstones as an aid to Provenancing Neolithic Axes". Read at the Annual Conference of the Ussher Society, January 1998 Although the quarry has not been identified, it has been suggested that the ''Gear'' (), a rock now submerged half a mile from the shore at

Penzance Penzance ( ; ) is a town, civil parish and port in the Penwith district of Cornwall, England, United Kingdom. It is the westernmost major town in Cornwall and is about west-southwest of Plymouth and west-southwest of London. Situated in the ...

, may be the site. A significant amount of trade is indicated as many have been found elsewhere in Britain.Pool, P. A. S. (1974) ''The History of the Town and Borough of Penzance.'' Penzance: The Corporation of Penzance.

Archaeology

References

Further reading