Luxullianite (also known as luxulyanite or luxulianite) is a rare type of porphyritic

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

, notable for the presence of clusters of radially-arranged acicular

tourmaline Tourmaline ( ) is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is a gemstone and can be found in a wide variety of colors. The ...

crystals enclosed by phenocrysts of orthoclase and

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

in a

matrix Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** ''The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...

of quartz, tourmaline,

alkali feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldspa ...

, brown

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

, and

cassiterite Cassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite was the chief tin ore throughout ancient history and remains t ...

. The name originates from the village of

Luxulyan Luxulyan (; kw, Logsulyan), also spelt Luxullian or Luxulian, is a village and civil parish in mid Cornwall, England, United Kingdom. The village lies four miles (6.5 km) northeast of St Austell and six miles (10 km) south of Bodmin. ...

Cornwall Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

, where this type of granite is found. An example may be seen in the

Duke of Wellington Arthur Wellesley, 1st Duke of Wellington, (1 May 1769 – 14 September 1852) was an Anglo-Irish soldier and Tory statesman who was one of the leading military and political figures of 19th-century Britain, serving twice as prime minister of ...

's tomb in

St Paul's Cathedral St Paul's Cathedral is an Anglican cathedral in London and is the seat of the Bishop of London. The cathedral serves as the mother church of the Diocese of London. It is on Ludgate Hill at the highest point of the City of London and is a Grad ...

London London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...

References

External links

Microscopic images of luxullianite. Siddall, R. (2014), Minerals Menu: a catalogue of minerals & textures in thin section
Granitic rocks Geology of Cornwall {{Petrology-stub