Guernsey, Bailiwick of Guernseyi

Regional Level Types
Guernsey	Island
Bailiwick of Guernsey	Crown Dependency

Guernsey (Guernésiais: Guernési) is an island in the English Channel off the coast of Normandy. It lies roughly north of Saint-Malo and to the west of Jersey and the Cotentin Peninsula. With several smaller nearby islands, it forms a jurisdiction within the Bailiwick of Guernsey, a British Crown dependency. The jurisdiction is made up of ten parishes on the island of Guernsey, three other inhabited islands (Herm, Jethou, and Lihou), and many small islets and rocks.

Geology:
"Guernsey is geologically complex but can be simplified into two halves (Figure 3). A larger southern half consists of Pentevrian metamorphic rocks separated by metasedimentary screens and with adamellites and granodiorites to the southwest. In the northern half, the Northern Igneous Complex is a series of five major plutonic bodies ranging in composition from gabbro through diorite (the most voluminous) to granodiorite and adamellite (Roach 1966).
The only record of mining is from the Parish of St Martin on the south coast where between 1842 - 1843 exploration and a little mining took place (as the Blanchelande Mines) before a successful anti-mining campaign caused the mines to disband in April 1843.
Four veins/lodes were described and promoted by William Row: "the district is rich in minerals and able to give a good return on investment", all within a four kilometre stretch of coastline. Amongst these veins were: a 1.5m wide silver-lead lode at Petit Bot showing gossan and soft calcite but "promising for silver and lead"; a copper lode lying between Icart Point and Petit Bot with gossan and pyrite and another silver-lead lode at Moulin Huet Bay which was 10 - 60cm wide with soft pyrite, gossan, silver and lead (Mourant & Warren 1934). These veins are now lost or are extremely difficult to reach; there is no associated spoil and only limited material in the local museum collections. One specimen from the Lukis collection (an early to mid nineteenth century rock and mineral collection) is labelled "argentic galena Guernsey" and comprises galena, iron-poor sphalerite, pyrite and traces of chalcopyrite, plus a little tetrahedrite in a calcite-quartz gangue. This assemblage is common in the islands and if the tetrahedrite is argentiferous (as in Jersey and Sark) then this specimen may well represent one of the silver-lead lodes.
Within the Northern Igneous Complex sulphide veinlets cut diorite at Baubigny near St Sampson and carry magnetite, ilmenite and abundant pyrite with small monoclinic pyrrhotite, mixed chalcopyrite-pyrrhotite and chalcopyrite with cubanite exsolution lamellae inclusions. Minor iron-rich sphalerite and molybdenite are also presnt. Similar assemblages from elsewhere in the Northern Igneous Complex have trace amounts of pentlandite, or as at Bouette Quarry (St Peter Port) consist of galena-sphalerite, pyrite and chalcopyrite, pyrrhotite and magnetite."
(http://www.rosiehardman.co.uk/taxev.htm)

Fossils

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Other Databases

Wikipedia:	https://en.wikipedia.org/wiki/Guernsey
Wikidata ID:	Q3311985

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References