The Merlin diamond field comprises 14 Devonian kimberlite pipes of which nine were subject to open cut mining between 1999 and 2006 producing 507,000 ct of diamonds. Small-scale mining also occurred at Merlin in 2017 and 2018 from the Ector deposit and from stockpiles.
Diamonds from Merlin have a high value due to the significant recovery (30% by weight) of gem quality stones and relatively high (55%) proportion of white gems. The largest diamond in Australia (105 carat and valued at US$525,000) was recovered in 2002 from the Gareth pipe at Merlin.
Exploration for diamonds has been at low levels in the Northern Territory since around 2008, although there remains significant potential for new discoveries. (The exploration potential is summarised in Hutchison (2012).
Other significant diamond occurrences in the southern McArthur Basin area include the Coanjula field and Abner Range diatreme. Diamond-bearing kimberlite dykes have also intruded the McArthur Basin northeast of Mataranka, at the Packsaddle and Blackjack prospects.
Jurassic-age diamond-bearing kimberlite pipes and dykes intrude Birrindudu Basin sediments near Timber Creek, and bulk sampling of the main pipe (TC-01) has recovered several hundred gem and industrial quality diamonds, with 40% appearing as gem quality, consisting of white, yellow, brown and pink varieties.