[1] It is most notable being a major source of opal, found near the town of Lightning Ridge, New South Wales.

[2] As a whole, the formation primarily consists of thinly bedded medium to fine sandstone, siltstone and mudstone, with sporadic coal seams.

These deposits are also the primary source of fossils within the formation, a large proportion of which are preserved as semi-precious opalized pseudomorphs.

The fauna found in lightning ridge indicates that the depositional environment of the Finch Clay Facies was in near-coastal freshwater lagoons.

[1] Indeterminate avialan, euornithopod, and sauropod remains that were once misidentified as brachiosaurid are present in New South Wales, Australia.