Although of low grade (5 to 14 carats per hundred ton), these mines were characterised by a high proportion (75–90%) of gem-quality stones, including colourless, fancy yellow, green and brown diamonds.
In 2023, following several years of exploration and resource definition, Australian owned private junior miner, India Bore Diamond Holdings Pty Ltd (IBDH) became the first company to officially re-commence licensed mining operations at Ellendale since 2015.
KDC then became reliant on its limited existing ore stockpiles while the ramp was repaired and made safe, thereby significantly reducing the output the E9 mine.
[4] The potential for economically re-opening of the collapsed and flooded hard rock pits at the E4 and E9 lamprorite pipes and/or associated colluvial deposits continues to be studied.
The number of carats so far mined in Ellendale’s alluvial beds falls far short of expectations based on the significant erosion of the diamond-bearing lamproites and geologist's calculations of the diamonds that have been liberated.
Geomorphological evidence strongly suggests that the eroded lamproites should have deposited a much greater volume of diamonds than have so far been found, fuelling renewed activity using new discovery and geophysical techniques in the field in recent years.
However, the discovery of the L-Channel drainage system some 20kms to the south has prompted a re-evaluation of this view, especially since a good portion of the diamonds recovered in Terrace 5 appear to have not been derived from any of the known lamproites within the supposed catchment.
Valley-fill sediments and wind-blown sand overlie the gravels to depths of up to 15 m, and the sequence provides evidence for dramatic climate change over the last 20 million years.
Plans to re-commence mining of the Terrace 5 alluvial deposits have been shelved pending further evaluation by Gibb River Diamonds.
The L-Channel is believed to run for some 22kms south passing by the E9 pipe and several other lampriorites including E7, E6 and E4 and is believed to have acted as a natural trap for millions of diamonds eroding from the rims of these diamondiferous lampriorites, suggesting a high likelihood of substantial diamond reserves remaining trapped and buried within the L-Channel.
The exact origins of diamonds discovered in alluvial beds proximal to the E12 pipe remain somewhat enigmatic, making the E12 region particularly intriguing for geologists.
Bulk samples collected from the E12 Alluvials area have produced diamond grades and average stone sizes significantly higher than recorded elsewhere in Terrace 5.
In 2020 IBDH reported that the company had discovered a population of diamonds from within the L-Channel that exhibited purple fluorescence under long wave ultraviolet light.