Diamonds recovered from Thorny River

Botswana Diamonds PLC

("Botswana Diamonds" or the "Company")

Diamonds recovered from the River Kimberlite at Thorny River

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

Highlights of the recovered kimberlitic indicators:

-     Eleven diamonds of good colour and clarity

-     Abundant indicators including G10, G9 and eclogitic garnets

-     Chromites and chromium diopsides

John Teeling, Chairman, commented: "The recovery of so many kimberlitic indicators and in particular diamonds, which are very rare to recover in small sample narrow reverse circulation drill holes is highly encouraging and bodes well for the potential commerciality of this exciting discovery".

Following a detailed ground geophysical programme in October 2020, 6, six-inch percussion reverse circulation holes were drilled into the newly discovered River Kimberlite pipe in the Limpopo Province of South Africa during November 2020.  A combined total of 39.5m intersected kimberlite while an additional 55m intersected a weathered kimberlite breccia. 

Samples from these holes were taken at one metre intervals and twenty of these totalling about 500kg were selected and submitted to an independent processing facility for assessment through screening, dense media separation and hand sorting.  11 diamonds, 172 G10 pyrope garnets, 623 G9 pyrope garnets, 555 eclogitic garnets, 438 chromites and 268 chromium diopsides (clinopyroxene) were recovered at sizes between
-1.0+0.3mm.  Recoveries of a specific mineral species were capped at 20 grains and thus this picture is a snapshot of the overall sample 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.  Of significance too is that these diamonds are all of good colour and clarity. 

The next step is a detailed core drilling programme which is planned for the dry season.

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 Cr2O3 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).

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.

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.