Ellendale 12 Alluvial Prospect

GIB 100%

• The Ellendale 12 (E12) alluvials are on GIB’s granted mining lease M04/475, approximately 3.5 km from the E9 Main Lights Stockpile resource.
• Substantial pitting, trenching, wide-diameter (Bauer) drilling and trial mining took place under the previous owners. GIB has this data.
• The 2023 valuation for E12 diamonds is US$796 per carat.
• GIB continues to assess the E12 alluvials as the Company progresses work on the nearby E9 Main Lights Stockpile and alluvial gravels.

Figure 1: Ellendale 12 location

1.0 Introduction

Bauer (ultra-wide diameter) drilling in 2006 conducted by Blina Diamonds in 2006-2007 identified a wide shallow east to west flowing alluvial channel south of the Ellendale 12 diatreme¹ (Figure 1). Gravels intersected by the Bauer program were up to 80cm thick and the highest diamond grades were intersected around the edges of the channel where gravels were best developed. 

Blina concluded that the diamonds recovered from the bulk sampling resemble those from both the E9 and E7 diatremes, plus a third unknown source. Blina named the gravels hosting this diamond population the E12 Alluvials.

2.0 Bulk Sampling

Initial bulk samples collected from the E12 alluvials produced diamond grades and stone sizes significantly higher than elsewhere in the Terrace 5 system¹. The diamond suite also included stones of distinctly different morphology and colour from those previously seen in the Ellendale area. Due to the occurrence of these distinct diamonds proximal to E12, Blina undertook a detailed Bauer drilling and bulk sampling operation. This bulk sampling showed the E12 diatreme is almost barren and is not the source of the alluvial diamond population¹.

Sampling returned a 2.71 carat green diamond plus two smaller stones with green colouration. These are the only green diamond recorded from Ellendale and their source is unknown.

Table 1: Bulk sample results, Ellendale 12 alluvials

(a) Cleaned diamond weight
(b) Diamonds recovered from the +1.5 -14mm size fraction
(c) +3.35 mm

3.0 Diamond Valuations

In February 2008 the E12 diamonds were submitted for valuation by Independent Diamond Valuers International (IDVI). This 428.3 carat parcel was valued at US$453/carat¹.

In April 2023 GIB announced updated diamond valuations from IDVI for the Ellendale Project². IDVI was responsible for sorting, grading, valuing and selling diamonds from the Ellendale Diamond Project (which includes E12) from 2002 to 2015. IDVI’s pricing system was used throughout this period and was utilised to provide the 2023 valuation. The original valuation or sale prices for these previously mined diamond parcels were used as the basis for this revaluation.
IDVI’s 2023 valuation gave an average E12 diamonds price of US$796 per carat. GIB considers the updated valuations in the report to be very attractive in terms of pricing.

Table 2: Alluvial Diamond Valuations – 2023

NB: all diamonds recovered above were in the in the 1.5-16mm range. The only exception to this were diamonds recovered from the Blina Alluvials Pit 82 which were recovered in the 1.2 to 14mm range.
Diamond breakage data is not available.

2.71 carat green diamond recovered during E12 sampling operations

152.43 carat parcel of stones recovered from the E12 alluvial 1

4.0 Permitting for Mining at E12

In May 2024 GIB announced the grant of mining lease M04/475 – 477³, of which M04/475 covers the E12 alluvials (Figure 1). These are the three key licenses at the heart of developing the Ellendale Diamond Project and cover the main portions of the historic workings at the E4 and E9 pipes, together with the extensively bulk-sampled E12 alluvials (Figure 1). The grant of these three mining leases is an important milestone in re-establishing diamond production at Ellendale.

GIB commissioned environmental consulting group Animal Plant Mineral Pty Ltd (APM) to undertake an environmental desktop study for the E12 and E9 Ellendale Project areas. This document is being used to determine the extent of any further studies required in order to obtain the various permits for mining at E12.

5.0 Summary

The E12 gravels are host to diamonds which are significantly larger and which occur in higher grades than are found elsewhere in the Terrace 5 alluvial system. The diamond population includes Fancy Yellow diamonds eroded from the E9 lamproite, and a green diamond population whose source is currently unknown. GIB is assessing the historic sampling information for these E12 gravels to determine their suitability for mining.

References: 

¹Record 2018/8 Geology, Resources and Exploration Potential of the Ellendale Diamond Project, West Kimberley, Western Australia (Geological Survey of Western Australia); by G. Boxer and G. Rocket. 2018. Click here

²Ellendale Project Reports Excellent New Diamond Valuations; GIB ASX Release dated 15 May 2023.

³Ellendale Diamond Project, WA: Grant of Mining Leases; Project Reports Excellent New Diamond Valuations; GIB ASX Release dated 21 May 2024.

⁴GIB Secures Ellendale Diamond Mine Leases; GIB ASX Release dated 23 December 2019.

Bulletin 132: The kimberlites and lamproites of Western Australia (Geological Survey of Western Australia); A.L. Jaques, J.D. Lewis and C.B. Smith. 

The information in this report that relates to current and previously reported exploration results and the JORC Exploration Target is based on information compiled by Mr. Jim Richards who is a Member of The Australasian Institute of Mining and Metallurgy and a Member of the Australian Institute of Geoscientists.  Mr. Richards is a Director of GIB River Diamonds Limited. Mr. Richards has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he is undertaking to qualify as Competent Person as defined in the 2012 Edition of the Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves.  Mr. Richards consents to the inclusion in the report of the matters based on the information in the form and context in which it appears.