India Bore Diamond Holdings Pty Ltd (IBDH) is a privately held Australian mining junior and Australia's newest producer of rare Fancy Coloured diamonds.
The company and the project both derive their name from the historic nearby stock watering hole of India Bore.
The Ellendale Diamond Field contains more than 50 known volcanic pipes, known as Lamproites. Not all of these pipes have brought diamonds to the surface and only 2 pipes, E4 and E9, have been commercially mined. These "hard rock" mines were abandoned in 2015 as diamond recoveries had fallen below economically viable levels.
Despite decades of endeavour by explorers and miners , no large scale alluvial deposits have ever been found at Ellendale and most geologists agree that only a small proportion of the diamonds eroded away from the primary lamprorite pipes have ever been recovered. By some expert calculations, more than 70 meters of rock and rubble has been eroded away from the tops of the pipes meaning that tens of millions of alluvial diamonds are buried beneath the sandy plains of the Ellendale diamond field. These are the "Lost Alluvials of Ellendale".
In 2015 IBDH determined that a large extinct river system lay hidden below the Ellendale plains. Detailed analysis of geophysical data showed that a deeply incised drainage system lay up to 15 metres below the current day surface. The system ran north to south, bisecting the Ellendale diamond field and passed very close to the major diamond producing lamproites of E9 and E4.
Further detailed analysis showed that this ancient channel system was in place before the diamond producing pipes erupted around 22 million years ago. The company believed that millions of diamonds brought to the surface by the volcanic pipes were likely washed into this pre-existing channel and many millions of diamonds remain trapped in the downstream gravel beds of this now extinct natural drainage system.
The newly identified channel was given the alphabetical prefix "L" to distinguish it from previously identified channels. A drilling and testing program was conducted by IBDH at key locations and by mid 2018 the company had recovered the first diamonds from a large bulk sample in the southern reaches of the channel. The diamonds recovered were of gem quality and included specimens of Ellendale's prized Fancy Yellows. The diamond morphology is typical of diamonds from both the E9 and E4 lamproites and exhibited clear evidence of alluvial transportation.
The diamondiferous basal gravel beds uncovered in the trenches contain large rounded river cobbles and boulders up to 900mm in diameter embedded in a sandy matrix. The gravel deposits lie between 6 and 16 metres below the current surface. These deposits are downstream of the Ellendale E9 and E4 lamproites, which are thought to be the primary source of the L-Channel diamonds. Diamonds up to 3+ carats have been recovered at commercially viable grades in 2 large exploration trenches within the L-Channel.
In a 2018 Mineralisation report to the West Australian Government, IBDH estimated an initial diamond resource of 1,300,000 carats based on a prudent analysis of all data and diamond recoveries in the L-Channel. A follow up trenching campaign in the 2019 season confirmed that the L-Channel contained several horizons of gravels with extensive basal gravel beds up to 3m thick.
A targeted drill and trench program was conducted in the 2020 season 11 kilometres north of the original bulk sample pits. This program also confirmed the existence of gravel beds containing diamonds.
IBDH has now tracked the L-Channel over a 15 km length and it is apparent that several sub-channels exist along a winding channel belt up to 300 metres wide containing gravel horizons up to 4 meters thick.
A grade control drill program was completed in June 2021 and a program of work is ongoing to demonstrate the continuity of these gravel deposits along a 15km strike.
Mining of the southern L-Channel is planned to commence in Q3 2021.
L Channel stockpiles await processing at the IBDH camp while the bulk sampling pit is simultaneously rehabilitated.
The basal gravels are characterised by large rounded river boulders ranging from 256mm to 900mm in a sandy matrix. These gravels have proven to be diamondiferous.
Various specimens of decayed volcanic tuff material can be found in the gravels. This material is easily weathered and broken down but its presence in the channel samples provides evidence that the channel passed very near volcanic vents
Assays from basal gravels indicate very high levels of Chromites, a key diamond indicator mineral. Chromites are relatively fragile and do not survive alluvial transportation over great distances. These well preserved Chromites show little transportation damage.
Large quartzite clasts including one massive sample weighing nearly 400kgs are distributed in the basal gravels. These clasts also indicate that the channel passes nearby volcanic vents.
Gravels are processed on site using water washing and density separation. 90% of water is re-cycled and no blasting, crushing or harsh chemicals are required in the recovery process. The washed waste gravels are returned to the pit within days in a near simultaneous rehabilitation process.
The Gouldian Finch was first recorded at the Project site in November 2018. An intense bushfire in the local Ellendale area at the time is thought to have concentrated the finches around the project area because of available water and large areas of natural feed grasses that had been protected from the fire.
The Goudian finch is semi-nomadic. The flat plains of the project area contains some seasonal foraging areas but the project area does not contain any rocky/hilly terrain which is the preferred nesting habitat of the Gouldian.
Nonetheless, the company has established an active Gouldian monitoring program.
A pair of Wedgetail Eagles (Aquila audax) drinking from a small puddle created by a water pipe check valve at the project site. The Wedgetail is the largest bird of prey found in Australia with a wingspan up to 2.84M across or almost 9 1/2 feet.
Local wildlife are easily observed near water sources during the dry season.
An Agile Wallaby (Macropus agilis) with joey captured by our thermal wildlife survey cameras at the project site. This wallaby is common in the area and a gregarious grazer.
The Australian Bustard (Ardeotis australis) also known locally as the Bush Turkey is a semi-nomadic bird standing up to 1 metre tall. These birds are commonly seen at the project site.
It is estimated that more than 1 million feral cats are in the Kimberley and they represent the most lethal threat to the native wildlife population. Each adult feral cat kills between five and ten native animals/birds a day. Despite the remote location of the project, the company has recorded a significant feral cat population in the area. The company is working with the WA authorities to initiate a feral cat control program.
Since being introduced into Queensland in the 1930's the poisonous Cane toad has continually spread westward and is now roughly half way across the Kimberley. They can travel up 50km in a year depending on the wet season.
Goannas, snakes, northern blue tongue lizards, and northern quolls are severely impacted and can suffer declines of 90% through to local extinctions, after the arrival of toads.
Feral dogs are a declared pest under the Biosecurity and Agriculture Management Act (2007). Wild dogs are less of a threat to Kimberley wildlife than feral cats but are occasionally seen in the project area.