Elaterite

Elaterite, also known as elastic bitumen or mineral caoutchouc, is a brown hydrocarbon varying somewhat in consistency, being sometimes soft, elastic and sticky, like India rubber, and occasionally hard and brittle. It occurs at Castleton in Derbyshire, in the lead mines of Odin and elsewhere. It is usually dark brown in color and slightly translucent. A substance of similar physical character is found in the Coorong district of South Australia, and is hence termed coorongite.