. "PHGV"@en . . "Phosphate-gravel"@en . "Phosphate-gravel - A type of phosphate-sediment. In the Rock Classification Scheme, it is one in which over 25% of clasts are larger than 2 mm. The grain size classes are defined in the same way as the siliciclastic sediments. British Geological Survey Research Report RR/99/03, section 4.1, table 10 and fig. 8. See also: silicate-gravel."@en . "Phosphate-gravel"@en . "stable"@en . . . .