In Maputo (Mozambique) next week

I will be in Maputo (Mozambique) next week (Monday to Wednesday, the 4th to the 6th April), focused on the country’s mineral industry. It’s a short stay and, unfortunately, limited to Maputo but it’s an opportunity to meet an talk about exploration and mining projects and opportunities (especially about, but not limited to, gems and diamonds, tantalite and other pegmatite deposits). Drop me a line to to set up a meeting.

Num retorno há muito desejado, estarei em Maputo (Moçambique) na próxima semana (segunda a quarta, 4 a 6 de Abril), focado na indústria mineira do País. É uma estadia muito curta e, infelizmente limitada a Maputo, mas é uma oportunidade para falar sobre projectos e oportunidades no de prospecção e mineração (especialmente em, mas não limitadas a, gemas e diamantes, tantalite e outros jazigos pegmatíticos). Contacte-me através do meu email para combinarmos uma reunião:

Going to PDAC – meet and talk

A last minute decision – I am traveling to Toronto to attend PDAC 2016.

It’s the perfect place to meet and talk: Angola, Mozambique, Brazil and Portugal, diamond and other gems, Nb-Ta and other pegmatite minerals, tungsten, gold, ferrous and base metal deposits, industrial minerals, natural stone. Challenges and opportunities.

Where and when can we meet?



Rubies from Mozambique – Field report published by GIA

I have had some involvement with mineral projects in Mozambique; I follow with attention news, especially on tantalum, diamonds – Diamonds discovered in Mozambique – Mustang Resources’ Save Project, coal – and rubies – Montepuez’ GEMFIELDS rubi mine – newest updates on the world’s single largest ruby and corundum deposit.

I have just came across an excellent GIA field report on the Mozambican Montepuez ruby mine, originally published at the 2015 Spring issue of GEMS & GEMOLOGY.


USGS Tantalum report (just published)

Two years ago I was involved in a very interesting tantalum project in the Republic of Congo (Brazzaville) – photo gallery here. I have since then followed with attention this metal’s market news (and its idiosyncrasies, being one of the 3TG minerals – subject to control under the conflict minerals framework).

USGS just published a report on the evolution of this metal’s market and production structure and origin in the last 15 years. It’s well worth reading (thanks to USGS for publishing the report) – you can get it here.

Montepuez’ GEMFIELDS rubi mine – newest updates on the world’s single largest ruby and corundum deposit

Discovered in 2009, Montepuez (Mozambique) is the world’s single largest ruby and corundum deposit. GEMFIELDS acquired a 75% interest in the concession in June 2011 from Mwiriti Lda. Montepuez Ruby Mining Lda (“MRM”) is the project operator and a joint venture between Gemfields and Mwiriti Lda. GEMFIEDLS released two documents on Montepuez by SRK Consulting.

According to the Reserves and Resources presentation:

  • 16 million carats (“mct”) produced to date.
  • To date a total of USD55 million has been invested , generating current total revenue of USD122 million.

Diamonds discovered in Mozambique – Mustang Resources’ Save Project

Diamonds (and rumours of their existence) are not new in Mozambique since colonial times (DIAMANG’s DIAMOC subsidiary had some activity in Mozambique). Later on, kimberlite were discovered/confirmed by soviet teams in the (then already independent) country.

Until now, the country has seen no industrial diamond production (or large scale diamond garimpo activity). That is perhaps about to change. Mustang Resources Limited (an Australian company) has just announced the discovery of alluvial diamonds in the gravels of their concessions along the Save River, in southwestern Mozambique. You may read the full news releases here: Mustang Discovers Diamonds – JORC Table 1 (June 16, 2015), Mustang Discovers Diamonds in Mozambique  (June 15, 2015) and their previous (June 10, 2015) Save River Diamonds Project Update; the company’s October 2014 presentation in OGIGROUPLTD PROJECTS_28Oct. Or, if rather prefer, at ASX website.

Mustang Resources Limited (ASX:MUS), formally called OGI Group Limited, is an ASX listed company focussing on diamond and graphite exploration and mining in Mozambique. You may refer to company’s website for further info on the project:; I also suggest you read the details of the information and comments about sampling and geological models included in Mustang Discovers Diamonds – JORC Table 1 (especially the last pages of the document).

Results and my comments (both very preliminary; the comments, of course, subjective)

16 diamonds (classified as gems) were recovered from 5 pits (9.68 ct with an average stone size of 0,60 ct/stone in a total of 4.732 m3).

It is a very early stage; it is a success to find diamonds in the first tests. Nonetheless, overall grade is small and stone size good (please note, these are preliminary results and they may not be considered representative of the potential  mineralization contained in the gravels).

The company is using a rotary pan as a concentration process. Although extensively used in South African gravel fields, I would rather use a DMS small scale plant (or a jig based system).


The Save River Diamonds Project is located in southern Mozambique, next to the border with Zimbabwe. The area of interest is along the Save River, after the confluence with the Runde River.

The licence areas are located where gravels, conglomerates and grits have been mapped on the surface. The tertiary to quaternary aged sediments are potentially associated with alluvial diamonds.

Metallogenical model (summary)

The geological model for this project is based on the Save and Runde Rivers having drained areas some 200 kms upstream with rich diamondiferous conglomerates and kimberlites (Murowa and Marange diamond fields in Zimbabwe) over millions of years.

The profile of the Save/Runde Rivers from the Marange/Murowa areas in Zimbabwe to the Save River Diamonds Project shows a very steep gradient resulting in a high energy environment which the Save River maintains until it reaches the confluence with the Runde River. The topography then changes to a gentle and almost flat surface at the confluence of the rivers. This has resulted in a massive deposition of gravels on the concession area which is a substantial 40km x 10km in size.

GEMFIELDS (AIM:GEM) rubies in Mozambique

Mozambique (Moçambique) contains a major gem province, until recently one of the world’s hidden treasures. If their tourmalines and other pegmatite related gems were already famous, ruby emerged as hot news in the last few years, with GEMFIELDS (AIM:GEM) producing mine  in Montepuez (northern Mozambique, Cabo Delgado province) – click here for their concession’s kmz (Google Earth format file shared via a Dropbox link).

In November 2014, Gemfields announced that an exceptional 40.23 carat rough ruby from Montepuez would form part of the December auction. The ruby was successfully sold, with the price remaining undisclosed given the principles on which Gemfields’ auctions are conducted – original statement here, also subject of a previous post in this blog.

Recently (original statement here),

Further to the announcement made on 7 December 2012, Gemfields plc, (AIM: GEM) is pleased to announce the completion of its acquisition of controlling interests in two additional ruby deposits in the Montepuez district of the Cabo Delgado province in Mozambique (the “Megaruma Licences”).

The conditions of the acquisition agreement have now been satisfied and the licences, valid for an initial period of 25 years, were formally issued by the Mozambican government on 22 September 2014 and 12 November 2014 respectively to a new company, Megaruma Mining Limitada (“Megaruma”), in which Gemfields is a 75% shareholder. The two licences, which do not border on one another, each share a boundary with Gemfields’ existing 75% owned Montepuez ruby deposit and cover approximately 19,000 hectares and 15,000 hectares respectively.

Previously, GEMFIELDS Annual Report and Financial Statements 2014 (June 30, 2014) ruby highlights:

Bulk sampling summary for 75% owned Montepuez Ruby Mining Limitada (“Montepuez”) in Mozambique for the year:

  • Approximately 6.5 million carats of ruby and corundum extracted (2013: 1.9 million carats) taking the total ruby and corundum extracted to 8.4 million carats.
  • Rough sales and auctions:
    • First-of-a-kind proprietary grading and sorting framework for rough rubies and corundum was well received at the inaugural auction in Singapore in June 2014;
    • First auction of rough ruby and corundum generated revenues of US$33.5 million at an average realised price of US$18.43 per carat; and
    • Next ruby auction is scheduled to take place before 31 December 2014 – results above.

GEMFIELDS is listed in London’s AIM (AIM:GEM) – check it here. You can also navigate into their website at

Sínese is a Lisbon-based consulting and engineering company specialised in Economic Geology. For further information or advice on mineral projects (Angola, Mozambique, Portugal, Brazil or elsewhere), contact us at or use the contact form.