Vinga is a small island outside Gothenburg's harbour entrance in Sweden. The 19th century Vinga Lighthouse is noted, not only as a beacon in the waterway of the Swedish west coast, but also as the place where the Swedish poet laureate

Evert Taube Axel Evert Taube (; 12 March 1890 – 31 January 1976) was a Swedish author, artist, composer and singer. He is widely regarded as one of Sweden's most respected musicians and the foremost troubadour of the Swedish ballad tradition in the 20th ce ...

grew up. Today Vinga is a tourist attraction, with boats to and from Gothenburg harbour.

Geology

The bedrock of Vinga is mostly made up of porphyrite (''porfyrit''), a

volcanic rock Volcanic rock (often shortened to volcanics in scientific contexts) is a rock formed from lava erupted from a volcano. In other words, it differs from other igneous rock by being of volcanic origin. Like all rock types, the concept of volcanic ...

with less

Silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

, SiO₂, than porphyry. The rock has a fine-grained structure, dark with lighter grains of

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) felds ...

and other minerals. The mineralogical composition of the Vinga porphyry classifies it as a

monzogranite Monzogranites are biotite granite rocks that are considered to be the final fractionation product of magma. Monzogranites are characteristically felsic (SiO2 > 73%, and FeO + MgO + TiO2 < 2.4), weakly quartz diorite Quartz diorite is an igneous, plutonic ( intrusive) rock, of felsic composition, with phaneritic texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with 10% or less potassium feldspar. Quartz Quartz is a hard, ...

. The northern part of the island contains orthopyroxene. The Vinga porphyry was created about 950 million years ago, when it penetrated the surrounding older

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures a ...

rock.

References

Southern Gothenburg Archipelago Listed buildings in Gothenburg Islands of Västra Götaland County {{Sweden-geo-stub