Chança River valley VMS cross section uncut video footage

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Chança River VMS deposit (Alentejo – Portugal, Iberian Pyrite Belt)

Last week I had the opportunity to document the Chança River valley VMS deposit cross section. This small outcropping deposit is located north of the old (now abandoned) São Domingos mine – Iberian Pyrite Belt.

The 5 min (uncut, 720p) video can be seen here (yes, I need to edit it as soon as I have some time – too many reports to write just now). It was captured in 4k resolution with a DJI Phantom IV Pro drone platform. The video was taken last week – May 9 – during a field visit to the location in the FIELD EXPLORATION WORKSHOP I – Hydrothermal alteration related with massive sulphide mineralization.

Additional photo gallery available here (just click the link), including pictures of the São Domingos mine.

Debaixo dum chapéu de ferro em Chança


Debaixo dum chapéu de ferro, no vale do rio Chança, a poucos quilómetros da antiga mina de São Domingos, o grupo do I Seminário de Prospeção do Projeto EXPLORA.

Já está disponível no blog a minha galeria de fotos deste dia.

Aproveito para agradecer à ideia e à estrutura deste seminário, com excelente conteúdo e óptima organização. Faço também minhas as palavras de Igor Morais da organização, deixando um agradecimento especial ao Prof. Jorge Relvas pela excelência da conferência apresentada sob o tema do seminário: alteração hidrotermal associada a sulfuretos maciços.

A todos os participantes, obrigado pelo óptimo ambiente.

Luís Chambel, Sínese

Chuva de diamantes? A erupção de kimberlitos explicada de forma simples

A WIRED, publicação dedicada à divulgação científica e tecnológica, acaba de publicar um artigo sobre a erupção de kimberlitos, as exóticas e raras rochas vulcânicas que arrastam os diamantes durante o seu processo eruptivo.

Vale a pena ler, mesmo quem, como eu, acha que sabe tudo.
Basta seguir o link aqui.


wrong, something is very wrong


Reporting to markets should (have to!) be complete, independent and competent.

Risk is a key factor; in most cases, along with commodity price, the most important variable defining a project’s value. The importance of a good estimate of the risk measure (the discount rate in DCF models) cannot be overemphasized.

Yet, something is wrong, very wrong:

  • In most cases (in a sample of 77 documents reporting pre-feasibility, feasibility studies and valuation exercises of operating assets), the magical discount rates used in DCF are 5% and 8%, accounting for 26% and 27% of the cases (10% accounts for 17%). In 75% of the analised cases, the used discount rate is ≤ 8%. Let’s say you are an investor, would you accept a lower than 8% rate in most mineral projects?
  • The 5% magical number is pervasive in gold projects. A new rule can almost be written; IF gold THEN 5%.
  • Reports include countless pages of technical minutia and detail of doubtful utility for the average investor; yet only a handful of them has any discussion or justification of the chosen discount rate.
  • Country risk is irrelevant; I will grant that the 77 sample is relatively small but the anecdotal evidence shows that the same risk is attributed to projects in the US and Canada or in Burkina Faso and Colombia.

Please bear in mind these are preliminary results; as more data is compiled, new trends may develop. Although I tried to have a random sample, diamond and gold projects may be overrepresented (20 and 21 out of 77, respectively).

I will present these and other results at SME’s Mining Finance Conference in NYC on May 1 and 2, a little more than a week from now. If you are attending, I would like to discuss in person the reasons behind this and how should this (can it?) be remediated – or shouldn’t reporting to markets be complete, independent and competent?

Being a member of SME and of the Society of Economic Geologists – SEG I will try to discuss this issue within these professional organisations. Your comments (in person or through online fora) are always welcome.