Alnön is an island in the

Gulf of Bothnia The Gulf of Bothnia (; ; ) is divided into the Bothnian Bay and the Bothnian Sea, and it is the northernmost arm of the Baltic Sea, between Finland's west coast ( East Bothnia) and the northern part of Sweden's east coast ( West Bothnia an ...

just outside

Sundsvall Sundsvall () is a city and the seat of Sundsvall Municipality in Västernorrland County, Sweden. It has a population of 58,807 as of 2020; more than 95,000 live in the municipal area. It is Sweden's 21st largest city by population. Old town i ...

Medelpad Medelpad ( or ) is a historical province or ''landskap'' in the north of Sweden. It borders Hälsingland, Härjedalen, Jämtland, Ångermanland and the Gulf of Bothnia. The province is a part of Norrland and as such considered to be Northe ...

, Sweden. It has an area of 67.79 km² and a permanent population of 8,417 (as of 31 December 2010), although its summertime inhabitants are about twice that number. Most of the island's inhabitants work in Sundsvall and other towns on the mainland. The island is 15 km long and 6 km wide on the widest spot. It is connected to the mainland by a bridge, which was the longest bridge in Sweden when it was opened in 1964. Evidences of habitation on the island predate the

Viking Age The Viking Age (about ) was the period during the Middle Ages when Norsemen known as Vikings undertook large-scale raiding, colonising, conquest, and trading throughout Europe and reached North America. The Viking Age applies not only to their ...

, and there are several

tumuli A tumulus (: tumuli) is a mound of Soil, earth and Rock (geology), stones raised over a grave or graves. Tumuli are also known as barrows, burial mounds, mounds, howes, or in Siberia and Central Asia as ''kurgans'', and may be found through ...

on the island from that period. The old stone church near the modern bridge was built in the 12th century. The island saw a population boom in the second half of the 19th century, due to the development of steam-driven

sawmill A sawmill (saw mill, saw-mill) or lumber mill is a facility where logging, logs are cut into lumber. Modern sawmills use a motorized saw to cut logs lengthwise to make long pieces, and crosswise to length depending on standard or custom sizes ...

s. In 1850 the island had 950 inhabitants, mainly farmers and fishermen, but by 1900 the population had grown to almost 7,000, following the establishment of 18 sawmills between 1860 and 1897. As result of decreased foreign trade during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

apatite Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of Hydroxide, OH−, Fluoride, F− and Chloride, Cl− ion, respectively, in the crystal. The formula of the admixture of ...

was mined in Alnön from 1943 to 1945. Apatite was separated by flotation but results were meager. While the separation process had improved in 1945 the end of the war the same year meant also apatite mining became unprofitable.

Geology

Alnö was affected some 570 million years ago by a massive

volcanic eruption A volcanic eruption occurs when material is expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior h ...

. The northeastern part of the island is rich in

carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...

minerals, and it is one of few areas in the world with a

carbonatite Carbonatite () is a type of intrusive rock, intrusive or extrusive rock, extrusive igneous rock defined by mineralogic composition consisting of greater than 50% carbonate minerals. Carbonatites may be confused with marble and may require geoche ...

volcanic complex. Its chemistry is very different from the ordinary granitic rock that form the rest of the island, resulting in a number of unusual minerals, such as

baryte Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate (Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

and

aegirine Aegirine is a member of the clinopyroxene group of inosilicate minerals. It is the sodium endmember of the aegirine– augite series. It has the chemical formula NaFeSi2O6, in which the iron is present as the ion Fe3+. In the aegirine–augite se ...

. The most famous of the

rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wale ...

s of Alnön is the ''alnoite'', named from the Island, which is a

lamprophyre Lamprophyres () are uncommon, small-volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks, and small intrusions. They are alkaline silica- undersaturated mafic or ultramafic rocks with high magnesium o ...

chiefly composed of

biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron- endmember annite, and the magnesium-endmember phlogopite; more al ...

phlogopite Phlogopite is a yellow, greenish, or reddish-brown member of the mica family of phyllosilicates. It is also known as magnesium mica. Phlogopite is the magnesium endmember of the biotite solid solution series, with the chemical formula KMg3AlSi3 ...

and

melilite Melilite refers to a mineral of the melilite group. Minerals of the group are solid solutions of several endmembers, the most important of which are gehlenite and åkermanite. A generalized formula for common melilite is ( Ca, Na)2( Al, Mg ...

as essential minerals, commonly with

olivine The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

and

clinopyroxene The pyroxenes (commonly abbreviated Px) are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula , where X represents ions of calcium (Ca), sodium (Na), iron (Fe ...

Perovskite Perovskite (pronunciation: ) is a calcium titanium oxide mineral composed of calcium titanate (chemical formula ). Its name is also applied to the class of compounds which have the same type of crystal structure as , known as the perovskite (stru ...

nepheline Nepheline, also called nephelite (), is a rock-forming mineral in the feldspathoid groupa silica-undersaturated aluminosilicate, Na3 K Al4 Si4 O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatit ...

and

garnet Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. Garnet minerals, while sharing similar physical and crystallographic properties, exhibit a wide range of chemical compositions, de ...

may also be present.

Diamond Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of e ...

s have also been found on Alnön, but only in very small amounts.

Sport

* Alnö IF

Notable citizens

*Vilma Abrahamsson, Football player *

Gunnar Hellström Gunnar Hellström (6 December 1928 – 28 November 2001) was a cinema of Sweden, Swedish actor and Film director, director. Partial filmography * ''While the City Sleeps (1950 film), While the City Sleeps'' (1950) - Young Man in Restaurant * ...

, Director * Tina Nordlund, Football player * Hjördis Schymberg, Opera singer * Andreas Yngvesson, Football player *

Helen Sjöholm Marie Helen Sjöholm (; born 10 July 1970) is a Swedish singer, actress and musical theatre performer who lives in Gamla Enskede in Stockholm. She grew up in Sundsvall and started to sing in choirs at an early age, working, among others, with Sw ...

, Singer and actress

References

External links

Rock samples from Alnön
{{DEFAULTSORT:Alnon Sundsvall Municipality Islands of Västernorrland County