For a Project overview watch our field video.
Figure 1: Location
GIB Blina Diamond Project – Key Points
8.43 carat Fancy Yellow diamond previously recovered from the Blina Project alluvials (GIB ground) during Terrace 5 sampling (Pit 82). This stone alone is valued at US$44,482.
1.0 Blina Diamond Project, WA GIB 100%
The Blina Diamond Project in the Ellendale Diamond Province of WA's Kimberley Region is 100% owned by Gibb River Diamonds Limited (‘GIB’ or the ‘Company’). The project consists of four granted mining leases and two exploration leases within an area of 161 km2, situated 100km east of Derby.
A diamond bearing alluvial palaeochannel named Terrace 5 extends over some 40km of the GIB project area, with channel widths of 200m to 500m. The largest diamond recovered to date from Terrace 5 weighed 8.43 carats (from Pit 82, Figure 1), with stones larger than two carats common.
The key to exploring the Terrace 5 diamondiferous channel is to find the best alluvial trap sites which are most likely to host the highest diamond grades, these trap sites usually occur around the sediment/bedrock contact. Gibb River Diamonds Limited has completed a ground geophysics survey using the latest in Ground Penetrating Radar (GPR) technology and the Company believes we now have a fast and inexpensive breakthrough technique which can discover these trap sites and their highly prospective diamondiferous gravels.
GIB has merged historic drilling, trenching, bulk sampling, trial mining, indicator mineral sampling and geophysical data with the latest state of the art GPR data to generate high-grade alluvial diamond trap site targets on the proven diamondiferous channels.
These targets will be tested this year via bulk sampling and trial mining, a field program will commence in March 2018: see field video.
1.1 Diamond Valuation
During the quarter, an independent appraisal on the data from a 1,497.57 carat parcel of diamonds previously mined from Terrace 5 was conducted. This gave a price of US$389 per carat (A$505 per carat). This is a 63% increase on the previous valuation of US$238 per carat made in April 2006.
This substantial price increase is mainly due to the greatly increased pricing of the fancy yellow component of the parcel which has gone up by 131% to US$3,391 per carat (A$4,403 per carat). The previous valuation of the Fancy Yellows in 2006 was US$1,466 per carat. The Fancy Yellow component now constitutes 62% of the value of the whole parcel (up from 50% in 2006).
The largest stone in the valuation parcel was a Fancy Yellow stone weighing 8.43cts. This diamond has an estimated value of US$44,482 (A$57,769) which is the equivalent of US$5,277 per carat (A$6,853 per carat).
1.2 Valuation Composition by Quality
The valuation parcel had a Gem content of 38%, Near-gem of 55% and Industrial of 7%. The combined Gem and Near-gem content of 93% could be considered high by world standards.
1.3 Blina Project Diamond Valuation Summary
The Board is very pleased with this new major increase in the valuation of the Terrace 5 diamonds. We believe it is an extremely significant development for the Company which will also have a positive effect on the economics of the Blina Diamond project. ASX Release
1.4 Terrace 5 JORC (2012) Exploration Target
The JORC (2012) Exploration Target for the Terrace 5 alluvials is from 700,000 to 1,000,000 cubic metres at a grade of 2.3 to 4.1 carats per cubic metre, for contained diamonds of 1.6 to 4.1 million carats.
Table 1 Exploration Target Summary
(carats per cubic metre)
Figure 2: Section View of Eroded Lamproite from E9
This Exploration Target is based on estimating the amount of ‘Missing Diamonds’ which have been eroded from the E9 pipe (Figure 2) and have ended up in the Terrace 5 palaeo channel (Figure 1). A full technical summary is detailed in the recent GIB ASX Release.
This maiden JORC Exploration Target demonstrates the potential of Terrace 5 to deliver very high grades on what would be a relatively simple, shallow, low capital cost and low operating cost alluvial mining process.
Previous explorers lacked a method of indirectly mapping the prospective bedrock-cover contact. The highly successful recent GIB geophysical survey using Ground Penetrating Radar may well prove to be a gamechanger for this project by quickly and inexpensively defining the highest quality diamond targets at this contact. The potential for discovering bonanza grades within these newly defined trap site targets presents an exciting and significant upside.
1.5 Nine ‘High Grade’ Diamond Targets Identified
By combining GPR and historic pitting and trenching data, GIB has identified two new discrete channels within Terrace 5. These have been named Channel 1 and Channel 2 (Figure 3). Previous testing on Channel 1 indicates it is strongly diamondiferous, Channel 2 is untested.
Channels 1 and 2 are deeper, and presumably older, than the other defined Terrace 5 gravels in the area. The historic bulk sampling which took place over the newly defined Channel 1 gave some of the best results within the Terrace 5 system, with grades up 10.5 carats per hundred cubic metres (cphm3), see Table 2.
Table 2: Bulk Sample Results from Channel 1
Diamond grade (carats per hundred m3)
Average diamond size (carats)
Largest Stone (carats)
Within Channels 1 and 2, GIB has identified nine new ‘High Grade’ targets, which the Company believes are the most prospective areas within the entire Terrace 5 system. These nine ‘High Grade’ targets have minimal overburden (2 to 8 metres), lie within proven diamondiferous channels and show up on the GPR as excellent potential alluvial trap sites.
Figure 3: High Grade Targets 1-9
Figure 4: High-Grade Targets 2 & 3 Ground Penetrating Radar with Interpretation
1.5.1 High-Grade Alluvial Diamond Trap Sites: Examples
The bonanza grades and returns that can be found within high-grade alluvial diamond trap sites make these systems a highly desirable target for alluvial diamond miners. An example of the type of high-grade pothole trap sites GIB is looking for at Blina is shown in the photo below taken at the Auchas Diamond Mine on the Orange River in Namibia.
Figure 5: Auchas Diamond Mine, Namibia. Potholes
1.6 Grant of Mining Leases De-Risks Project
All four of the company’s mining lease applications were granted. This is a major step forward for the Company and reflects the considerable work and preparation which has gone into the Blina Diamond Project to date.
The grant of these leases was assisted by securing two historic Mining Agreements with the following groups:
As a result of the grant of these mining leases, the project has been significantly de-risked. The company now has the ability to immediately transition to a full-scale mining operation, should commercial diamond grades be encountered during the upcoming field seasons sampling operations.
1.7 Lookahead Work Program
The Company is currently involved in planning and permitting activities with the aim of conducting bulk sampling and trial mining operations at Blina in 2018. For operational reasons, it is planned to only conduct earth moving and treatment during the dry season (April to December).
The on-site work program will commence in March 2018. Below are some of the action items which are either completed, underway or planned: