Diamonds recovered from River Kimberlite Extension

Botswana Diamonds PLC

("Botswana Diamonds" or the "Company")

Diamonds recovered from the River Kimberlite Extension at Thorny River

Botswana Diamonds, the AIM and BSE listed diamond explorer, is pleased to announce that four high-quality diamonds and abundant kimberlitic indicators were recovered from drill samples at the recently discovered River Kimberlite Extension at Thorny River in the Limpopo Province of South Africa.

Highlights

-     Four diamonds of good colour and clarity

-     Abundant diamond indicators including G10, G9 and eclogitic garnets

-     The River Extension blow is contiguous with the diamondiferous River blow

-     New drilling programme to begin by end August

As previously announced in May earlier this year, a total of 71 metres of kimberlite was intersected in 12 percussion holes in the newly discovered River kimberlite extension in May 2021, with an additional 19 metres of kimberlitic breccia. The widest kimberlite down-the-hole intersection was 18 metres.  The drilling programme outlined a significant swell on the kimberlite dyke with a minimum strike length of 75 metres.  The River Extension blow is contiguous with the diamondiferous River Blow which was discovered by the company in November 2020.  

Samples from these holes were taken at one metre intervals and twelve of these totalling about 320kg were selected and submitted to an independent processing facility for assessment through screening, dense media separation and hand sorting. Four diamonds of good colour, clarity and of commercial quality were recovered along with extensive diamond indicators minerals.

A further percussion drilling programme to assess the area between the River and River Extension will begin within a month.

John Teeling, Chairman, commented: "The recovery of high-quality diamonds and so many diamond indicators is very rare. The diamonds are of good quality. It is unusual to recover diamonds from a small sample of narrow reverse circulation drill holes so it bodes well for the potential of the Thorny River project.  Even more encouraging is that the size of the kimberlite from which the diamonds were recovered, is itself expanding.  We will commence drilling the area between the two blows towards the end of August."

Details of sample analysis

4 diamonds, 211 G10 pyrope garnets, 219 G9 pyrope garnets, 226 eclogitic garnets, 215 chromites, 154 ilmenites and 172 chromium diopsides (clinopyroxene) were recovered at sizes between -1.0+0.3mm.  Recoveries of a specific mineral types were capped at 20 grains and thus this picture is a snapshot of the overall rich kimberlitic indicator content.  Importantly, all the samples contained abundant kimberlitic indicators. The diamonds are all notably of good colour and clarity and are of commercial quality and in high demand by the market. The diamonds were not weighed as the sample size was small and they are not representative of a possible population.

Pyrope garnets are common in peridotite xenoliths from kimberlite pipes, some of which are diamond-bearing.  Pyrope found in association with diamond commonly has a Chromium Oxide content of three to eight percent which imparts a distinctive violet to deep purple colouration.  These are called G10 and G9 pyrope garnets.  Eclogites typically result from high to ultrahigh pressure metamorphism of mafic rocks at low thermal gradients as they were subducted to the upper mantle in a subduction zone.  Garnets found in eclogitic xenoliths tend to have a deep orange colour.  Diamonds in kimberlite come from both peridotitic and eclogitic xenoliths so the abundance of both types of garnet in this sample is noteworthy and this is supported by the recovery of diamonds from a relatively small drill sample. 

This release has been approved by James Campbell, Managing Director of Botswana Diamonds plc, a qualified geologist (Pr.Sci.Nat), a Member of the Geological Society of South Africa, a Fellow of the Southern African Institute of Mining and Metallurgy, a Fellow of the Institute of Materials, Metals and Mining (UK) and with over 35-years' experience in the diamond sector. 

This announcement contains inside information for the purposes of Article 7 of Regulation (EU) 596/2014. The person who arranged for the release of this announcement on behalf of the Company was James Campbell, Director

A copy of this announcement is available on the Company's website, at www.botswanadiamonds.co.uk

Enquiries:

www.botswanadiamonds.co.uk

ENDS

Glossary

Mafic rock: A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in colour, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro

Pyrope garnet: Pyrope is the most well-known gemstone form of Garnet. Its dark, blood-red colour is distinct and attractive, and makes a fine Garnet gemstone. In the gem trade, the term Pyrope is rarely used on its own. It is either generically called "Garnet", or "Pyrope Garnet"

G9 and 10 garnets: Pyrope garnet found in association with diamond commonly has a Chromium Oxide content of 3-8%, which imparts a distinctive violet to deep purple colouration (often with a greenish tinge) and because of this is often used as a kimberlite indicator mineral in areas where erosive activity makes pin-pointing the origin of the pipe difficult. These varieties are known as chrome-pyrope, or G9/G10 garnets.

Eclogitic garnets: The typical eclogite mineral assemblage is garnet (pyrope to almandine) plus clinopyroxene (omphacite). Eclogites record pressures over 1.2 GPa (170,000 psi), 45 km (28 mi) depth at about 400 to 1,000 °C (752 to 1,832 °F) and usually over 600-650 °C (1,112-1,202 °F).

GPa: A unit of pressure equal to 10⁹ pascals.

Peridotitic xenolith: A xenolith is a piece of rock trapped in another type of rock.  Xenoliths and xenocrysts are often identified by the names of the two rock types involved. A peridotite xenolith in a basaltic lava flow, for instance, means a chunk of the rock peridotite is embedded in basalt rock. The peridotite is usually yellow and dense, while the basalt is usually grey and light.

Psi: Pounds per square inch (PSI) is a common unit of pressure.

Subduction: Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the heavier plate dives beneath the second plate and sinks into the mantle.