Elaterite, also known as Aeonite, 'elastic bitumen' , 'mineral caoutchouc' or Wurtzilite.
Elaterite is a brown hydrocarbon varying somewhat in consistency, being sometimes soft, elastic and sticky, like India rubber, and occasionally hard and brittle. 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.
Occurrence in nature
Strawberry, Utah, USA: Occurs in the Indian Canyon, Sams Canyon, Dry Fork, and Lake canyon, tributaries of the Strawberry river in Duchesne County. It occurs in vertical veins from one to twenty-two inches wide, twenty to two hundred feet high, and a maximum length of three and one quarter miles" Also flows from the ground in a soft elastic form at various locations along the Strawberry River
Castleton in Derbyshire: Windy Knoll Cave. The lead mines of Odin.