"stable"@en . . . . . "SILICR"@en . "Siliceous rock - In the Rock Classification Scheme, these are rocks which are composed of more than 50% silica of biogenic or chemical origin. This is the lithified equivalent of non-clastic siliceous sediment. British Geological Survey Research Report RR/99/03, section 8.2 and fig. 12."@en . "Siliceous rock"@en . . "Siliceous rock"@en . . . . .