"stable"@en . . . . . "ABBI"@en . "Ironstone."@en . . "Ironstone. Stratified bedrock. Occurs onshore. Deposited during the Duckmantian Substage (Carboniferous Period) (318-314.75 Ma BP)."@en . . "Airdrie Blackband Ironstone (Central Coalfield)"@en . "Airdrie Blackband Ironstone (Central Coalfield)"@en . "318.0"^^ . "314.75"^^ . . .