Botryoidal phosphates and asphaltum occur in a small irregular vein that is 10 centimetres to 30 centimetres wide and outcrops at intervals over a length of about 30 metres. The vein occurs in a Tertiary amygdaloidal and vesicular andesitic flow that overlies sandstone and shale. Although described as a vein, it has been noted that the occurrence appears to be a layer between two lava flows. The asphaltum has been classified as asphaltic pyrobitumen while the phosphates have been identified as collinsite and quercyite.