El Soldado ( The Soldier) is a peculiar copper deposit in the Chilean Andes with mineralization believed be associated to primary lithological factors (such as composition and porosity), structure, metamorphism, granitic intrusion, petroleum, yes, petroleum and bacteria. I will get into the details of the interesting and debatable geology in a next post but first let me show you what it looks like there. Chile and its Andes mountains are special, and it was a fantastic experience to visit such an interesting and historic mine above the clouds.
I have made mention of this mine in a previous post (here) before. It is an Anglo American operation situated 130 km north of Santiago and at 600 m above sea level. This operation produces around 50 000 t of copper per year and has around 175 Mt in reserves @ 0.8 % Cu.
A beautiful setting for the core yard and sampling facilities with the Andes canvassing the background.
Geological continuity in the context of resource modeling and estimation usually refers to the lithological (sometimes structural) features that define the ore zone with a defined consistency. This might be defined, for example, by a particular sandstone unit which consistently hosts uranium mineralization over a certain area, a vein (ore shoot) hosting gold mineralization or even a contact area between to rock types (skarn deposit). Value continuity however, is defined as the degree of consistency with which the value of the mineralization itself is consistent within a particular deposit. This value speaks of grade, thickness and could even be extended to geo-metallurgical consistency (the continuity of similar mineralogy). But why do we need to differentiate between these two concepts as opposed to just pure continuity?
Image of the El Soldado pit from the viewing platform. This image from the mintecminesite blog
There seems to be a lot of interest in magmatic sulphide deposits from readers, or should I rather say an interest to better understand these interesting deposits. My last post focused on the central role of sulphur in these magmatic systems, how the sulphide portion of the magma separates from the silicate portion and then how the sulphide melt deposits itself within the magma chamber. We also spoke about how Fe gets into the sulphide melt. But what about the important stuff, the nickel, copper and PGE?
ARM’s nickel sulphide Nkomati mine in South Africa. It’s Cu/Ni ratio ma suggest Bushveld lineage…
A colleague and I visited a university geology department in the vicinity of a project we were working to do a presentation on the geology of the project. We had been invited by a professor who’s research interests were amongst other things, mafic-ultramafic rocks and he had invited us as our project was hosted by such. He relayed an interesting story to us that day: Final-year students in the department were required to complete a research project and a student had approached the professor and told him that he is interested in doing a project about ultramafic rocks. The professor immediately retorted: “No! Ultramafic are only for the masters!” The professor was of course not talking about Masters’ degree students but referring to the dedication and possible the intelligence required to understand these rock types and their associated deposits.
Today I am writing from the field, connecting with the fastest, most rural internet connection I have every had the privilege of connecting to! And what a day it was! The site where I am currently working is one of the few near-equatorial, semi arid regions in the world and is far from anything and everything, they way I love it! Apart from a very short rainy season, the rest of the year is blistering hot and dry. From about 10 am the temperature starts flirting with 40C and then it only goes up. I made the mistake of mapping the largest mountain in the region over the heat of the day and at one point had a real fear that my heart was going to explode! Most of the way was through thorn thicket and wood land, looking for fresh outcrop, a rare commodity in these parts.
The view from the top of the mountain.
Kolomela is one of Anglo American’s large iron ore producing mines. This open cast operation is situated near the town of Postmasburg in the Northern Cape province of South Africa. Today’s post is a stunning blast sequences as published on Anglo’s Flickr feed.
According to Anglo “exploration on this project dates back to the 1950s, although the first impact studies were only undertaken in 2001. Construction started in late 2008 following the receipt of relevant permits. At the end of December 2011 the mine was 98% complete. The mine will achieve full production in 2013. The Kolomela mine ore bodies comprise hard, high-grade, conglomeratic and laminated haematite orebodies. The ores have been preserved as three separate orebodies within basinal and graben structures up to 2km long, 400m wide and 300m deep. Kolomela’s lump ratio is expected to be 60:40. Kolomela mine’s Ore Reserves amounted to 203.4Mt at 31 December 2011, while Mineral Resources (excluding reserves) were 162.3Mt at 63.6% Fe. The current LOM is 28 years”.
You can get more info on this project and the source of this info here and here.