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Alum Shale Formation
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<p>The Alum Shale Formation (also known as alum schist and alum slate) is a <a href="/facts/Formation_(geology)/mMhpw4G2">formation</a> of <a href="/facts/Black_shale/bsIhqY5F">black shale</a> of <a href="/facts/Miaolingian/5NcBhyEU">Miaolingian</a> (Middle <a href="/facts/Cambrian/jIfzKtod">Cambrian</a>) to <a href="/facts/Tremadocian/d3lTcsDl">Tremadocian</a> (Lower <a href="/facts/Ordovician/BjMrLIEA">Ordovician</a>) in age found predominantly in southern Scandinavia. It is <a href="/facts/Shale/bsIhqY5F">shale</a> or clay <a href="/facts/Slate/hSVHL6Lj">slate</a> containing <a href="/facts/Pyrite/41CYREyr">pyrite</a>. Decomposition of pyrite by weathering forms <a href="/facts/Sulfuric_acid/Wom6fymJ">sulfuric acid</a>, which acts on <a href="/facts/Potash/4e2vBL9L">potash</a> and <a href="/facts/Aluminium_oxide/wXM9P6pI">alumina</a> constituents to form <a href="/facts/Alum/ULAn0XRB">alum</a>, which often occurs as <a href="/facts/Efflorescence/MVErNa6p">efflorescences</a> on the rock <a href="/facts/Outcrop/3MC1NG4y">outcrop</a>. </p><p>As the formation contains <a href="/facts/Kerogen/LjfWR4pQ">kerogen</a> originated from <a href="/facts/Algae/U1ftVKU3">algae</a>, it is also classified as <a href="/facts/Marinite/aFxqxNbF">marinite</a>-type <a href="/facts/Oil_shale/WSREUH8t">oil shale</a>. At the same time it is rich in <a href="/facts/Aromatic_hydrocarbon/3EXq8Tgf">aromatic hydrocarbon</a> attributed to post-depositional <a href="/facts/Irradiation/fHW0QNAa">irradiation</a> damage to saturated hydrocarbons, induced by <a href="/facts/Uranium/n2sGWBzU">uranium</a> concentration in the shale. Alum shale also contains enhanced levels of <a href="/facts/Radium/VWo5gkzn">radium</a> as a result of uranium <a href="/facts/Radioactive_decay/Ya6FVjt4">decay</a>. Between 1950 and 1989, Sweden used alum shale for the uranium production. </p><p>8502 specimens of <a href="/facts/Trilobite/Tk8ppaKc">trilobite</a>-<a href="/facts/Agnostoidea/ujhGBKsw">agnostoid</a> fauna were found in the <a href="/facts/Furongian/3A6Ke7z5">Furongian</a> strata of this formation in <a href="/facts/Bornholm/mYKGqdPg">Bornholm</a>, <a href="/facts/Denmark/KVtykzsw">Denmark</a>. Most of them are disarticulated sclerites. Described gerena include <i>Ctenopyge</i>, <i>Eurycare</i>, <i>Leptoplastus</i>, <i><a href="/facts/Olenus/F7An0Yw0">Olenus</a></i>, <i>Parabolina</i>, <i><a href="/facts/Peltura/owmuJV8T">Peltura</a></i>, <i>Protopeltura</i>, <i>Sphaerophthalmus</i>, <i><a href="/facts/Lotagnostus/yChJYYrG">Lotagnostus</a></i> and <i>Triangulopyge</i>. </p>