Comets, Asteroids and the Sow’s Ear

Venture capitalists and entrepreneurs not only want to make lots of money but they want to change the world and some even believe they can. Bryan Johnson has committed a substantial portion of his wealth, $100 million, to what he calls “crazy” projects. One initiative is to capture an asteroid and mine it. Mr Johnson made his money founding and then selling Braintree, an online payment provider.

Earlier this month a spacecraft called Rosetta finally caught up with a mysterious comet with the less beautiful name 67P/Churyumov-Gerasimenko and lowered an automated probe onto the boulder-strewn surface of this globular fragment of ice, dust and rocks less than three miles across. It took more than a decade, and a looping trajectory that covered four billion miles, before the Rosetta spacecraft launched by the European Space Agency caught up with the mysterious comet near Jupiter in August.

These great solar ambitions and achievements made me think about how little we know about our own planet and how ineffective we are still in trying to explore the vast mineral riches within the earth’s crust. It also made me compare the crazy risk-taking of Bryan Johnson at one end of the spectrum with the sclerotic high net worth investors and fund managers and now many mining companies which are terrified of risking capital to explore for metal deposits deep beneath the surface.

I mentioned before of the danger of being sucked into investment in poor quality mine development projects when metal prices surge. The reason such deposits have not been developed in the past is because you still can’t turn a sow’s ear into a silk purse but you might delude yourself for a while. The only way now to find quality mining assets in most metallogenic belts is to search for and discover blind deposits and it is far cheaper than the cost of chasing asteroids and comets.

The Iberian Pyrite Belt which runs from southern Portugal into Andalusia is a monster in terms of metal endowment and arguably contains the largest massive sulphide province in the world. These volcanogenic massive sulphides (VMS) contain mostly iron sulphides called pyrite but they also contain variable and locally substantial riches in polymetallic concentrations of zinc, copper, lead and also silver and gold and even tin. By the turn of the century the metal treasure trove of the Iberian Pyrite Belt both mined and in the ground stood at 1.7 billion tonnes of metal suphides containing 14.6 million tonnes of copper, 13 million tonnes of lead, 35 million tonnes of zinc, 16,100 tonnes of silver and 880 tonnes of gold. So is there more blind world class deposit like Neves Corvo to be found deeper beneath the surface? We will not know unless we look and we will not be able to look unless there is venture capitalists and entrepreneurs willing to finance the expeditions.

There has been mining in the Iberian Pyrite Belt since Phoenican times and a phase of the bronze age before it was discovered that adding tin to copper formed a harder type of bronze. It is a long time to find and exploit all the outcropping and near surface deposits which made the grade. The blind Neves Corvo, which alone is comparable in metal content to the whole of the Canadian and Australian VMS deposits put together, was discovered in 1977. The copper and tin rich ore bodies of Neves Corvo averaged14.5 per cent combined placing it among the richest copper deposits in the world. Other blind deposits such as Gavião, Lagoa Salgado, Neves Corvo, Cabezo, Migollas, Los Frailles , Valverde and Las Cruces have been discovered in the Iberian Pyrite Belt mostly by geophysics and specifically using gravimetry. I believe for one that we have only scratched the surface and that the IPB, particularly over the last 20 years, has been very much underexplored and during a time when exploration technology and specifically geophysics and geological understanding of these volcanogenic mineralizing systems has advanced greatly.

Hudbay has operated in the Flin Flon Greenstone Belt, which straddles the Saskatchewan- Manitoba border in Canada, for over 85 years. The Flin Flon camp contains 16 known VMS deposits with an aggregate of 115 million tonnes. The Snow Lake mining camp about 100 kilometres further east in Manitoba contains nine known deposits with a total of 45 million tonnes. The zinc and gold rich Lalor mine is the largest VMS deposit in the Snow Lake camp. In March, 2007, the Lalor VMS polymetallic deposit of zinc, copper, gold, silver and lead was discovered by Hudbay approximately three kilometres northwest of Chisel North mine in Snow lake, Manitoba. The discovery drill-hole cut high-grade zinc mineralization at a depth of about 800 metres below surface and initiated the delineation of a 14.4 million tonne deposit. Initial mine production began in August 2012 and the mine reached commercial production in the third quarter of 2014.

The discovery drill-hole at Lalor tested a Crone fixed-loop time domain electromagnetic (DPEM) anomaly identified in 2003. Once the discovery was made it was obvious to investigate if the Lalor deposit could be detected by airborne geophysics to find an effective tool to further explore the camp. Lalor eluded detection by helicopter time-domain EM surveys using the newest and latest VTEM system because it fell below the 400-metre depth of investigation imposed by this geophysical technology. In November 2009 Geotech conducted the first Airborne Electromagnetic survey to successfully detect Lalor. The fact that in detail that it was a new ZTEM passive-EM system is not important as much as it shows that the technology is available.


Alan Vowles and Peter Dueck of Hudbay made the point recently at the British Colombia Geophysical Fall symposium in Vancouver (Exploration for Deep VMS Ore bodies: The Hudbay Lalor Case Study) that there are important lessons learned because as exploration geologists we need to consider the type of data available and what are the limits of that data. Realistically there could be other world-class deposits in areas that were previously considered adequately explored or considered to have little potential. I am attracted to the Portuguese side of the IPB for simple business reasons which might offend some Andalusians but first I need to find a crazy venture capitalist.

Maybe now is the time to apply such testosterone technologies to the Iberian Pyrite Belt to find the silk purses beneath the surface. Mining companies such as Hudbay and Doe Run and indeed New Boliden in Sweden and at the Navan Mine in Ireland which can sustain their business in major mining camps for many, many decades by the application of knowledge, experience of dedicated teams of scientists with and a generous helping of belief and perseverance deserve our greatest respect.

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