Härsbacka mine ( sv, Härsbacka gruva) is a

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 ...

and

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) feldsp ...

mine. It was once Sweden's foremost quartz mine. The mine was closed in 1946. The quartz and

mined in Härsbacka are the main constituent of a large

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...

dyke. This pegmatite dyke dips about 60 to 70° to the southeast and has a maximum thickness of 37 m. While quartz and feldspar are mostly mixed, pure zones of either occur. Most feldspar is pink

microcline Microcline (KAlSi3O8) is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slow ...

perthite Perthite is used to describe an intergrowth of two feldspars: a host grain of potassium-rich alkali feldspar (near K-feldspar, KAlSi3O8, in composition) includes exsolved lamellae or irregular intergrowths of sodic alkali feldspar (near albite, Na ...

and much lesser amounts are white

oligoclase Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters it is intermediate between albite ( Na Al Si3 O8) and anorthite ( CaAl2Si2O8). The albite:an ...

. There are lesser quantities 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 alumino ...

garnet Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different s ...

molybdenite Molybdenite is a mineral of molybdenum disulfide, Mo S2. Similar in appearance and feel to graphite, molybdenite has a lubricating effect that is a consequence of its layered structure. The atomic structure consists of a sheet of molybdenum ato ...

and

fluorite Fluorite (also called fluorspar) is the mineral form of calcium fluoride, CaF2. It belongs to the halide minerals. It crystallizes in isometric cubic habit, although octahedral and more complex isometric forms are not uncommon. The Mohs sca ...

. About 230,000 tons of quartz have been mined in total from Härsbacka mine. In 1947 the mine was bought by Statens Vattenfallverk to turn it into an oil storage depot and it functioned as such until 1985 when it was emptied. Since 1997 the mine is fully flooded by

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

. In 2021 the

Geological Survey of Sweden Geological Survey of Sweden ( sv, Sveriges geologiska undersökning, SGU) is a Swedish government agency that was founded in 1858 dealing with questions about the nature of the geological and mineral management in Sweden. The institution has the ...

was tasked with investigating contaminants in the mine.

References

{{Reflist 1895 establishments in Sweden 1946 disestablishments in Sweden Feldspar mines in Sweden Underground mines in Sweden Quartz mines in Sweden Österåker Municipality Former mines in Sweden Environmental issues in Sweden Pegmatite mines