- published: 08 Jun 2013
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Phosphorite, phosphate rock or rock phosphate is a non-detrital sedimentary rock which contains high amounts of phosphate bearing minerals. The phosphate content of phosphorite is at least 15 to 20%, which is a large enrichment over the typical sedimentary rock content of less than 0.2%. The phosphate is present as fluorapatite Ca5(PO4)3F (CFA) typically in cryptocrystalline masses (grain sizes < 1 μm) referred to as collophane. It is also present hydroxyapatite Ca5(PO4)3OH, which is often dissolved from vertebrate bones and teeth, whereas fluorapatite can originate from hydrothermal veins. Other sources also include chemically dissolved phosphate minerals from igneous and metamorphic rocks. Phosphorite deposits often occur in extensive layers, which cumulatively cover tens of thousands of square kilometres of the Earth's crust.
Limestones and mudstones are common phosphate bearing rocks. Phosphate rich sedimentary rocks can occur in dark brown to black beds, ranging from centimeter sized laminae to beds that are several meteres in thickness. Although these thick beds can exist they are rarely only composed of phosphatic sedimentary rocks. Phosphatic sedimentary rocks are commonly accompanied by or interbedded with shales, cherts, limestone, dolomites and sometimes sandstone. These layers contain the same textures and structures as fine grained limestones and may represent diagenetic replacements of carbonate minerals by phosphates. They also can be composed of peloids, ooids, fossils, and clasts that are made up of apatite. There are some phosphorites that are very small and have no distinctive granular textures. This means that their textures are similar to that of collophane, or fine micrite-like texture. Phosphatic grains may be accompanied by organic matter, clay minerals, silt sized detrial grains, and pyrite. Peloidal or pelletal phosphorites occur normally; whereas oolitic phosphorites are not common.
Chris Castle (born January 29, 1976, in Sandusky, Ohio) is a folk/Americana singer-songwriter. Cleveland Magazine has described his writing as an "authentic connection to the world-weary soul of American roots music", while The New London Day's Rick Koster calls Castle "a visionary songwriter" and "a tunesmith of almost scary vision, narrative acumen and hooky instinct".
Born in Sandusky, Ohio, in 1976, Castle's family moved to the village of New London, Ohio around the time he was four. His parents had migrated to Ohio from eastern Kentucky in the late sixties, and Castle was exposed to Appalachian Music from a very early age. His father (a Vietnam War veteran) committed suicide when Castle was nine years old; a theme that would later inspire Castle's first official single and video, Both Ends of A Gun.
Castle spent his teen years as a staff-writer in Nashville, Tennessee, working under such notable writers as; Casey Kelly (The Cowboy Rides Away), Wood Newton (Bobbie Sue), and Earl Bud Lee (Friends in Low Places). At twenty-one, he would leave Music Row to again perform in bars and coffeehouses in northern Ohio.