Geology & GeoMetallurgy

Geology & GeoMetallurgy 2017-04-04T06:58:01+00:00
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How to Find Ore and Mineral Deposits (3 replies)

John Koenig
2 years ago
John Koenig 2 years ago

Let's talk about drilling geometry optimization, mineralization intersection geometry and structural vectoring as important drivers to mineral target development. Adding an orientation vector to the sample location is a very useful thing, assuming you have the ability to do so. Very little in geology is homogenous, and knowing where your mineralization is trending can save you quite a bit of wasted time and money. This assumes, of course, that your driller is cooperative and skilled enough to not spin the core and your geologist on site knows how to orient the core. Drilling on angle makes orientation a bit easier if there is some horizontal bedding to use, but otherwise, you’re talking about some much more complicated orientation techniques that many would probably not want to fool with. I suppose your best bet would be to lower a bore camera with a compass down to the sample zone and find some trend in the grains to orient by. When you just spent $50,000 on a core hole, trying to get management to approve another $10,000 for geophysical in the current market can be challenging, even if in the long run it will save money. Focus seems to be on the immediate, not so much the long term.

Maya Rothman
2 years ago
Maya Rothman 2 years ago

I know a bit about this subject, having used, at one time or another, just about all the techniques used for down (or UP!) drill hole surveying and sampling. (Yes, even acid etch glass tubes for hole deviation surveys.) I have also used Vulcan and other similar systems to resolve drill, geology and structural data so it is more visually useful.

Oriented core drilling is slow and expensive, and is not needed in every hole. Used for many years in engineering work (slope stability, excavation design etc) it is seen more in mining circles now than before. The fact is, it works but is not a new tool. Oriented core has limitations in many instances which would therefore limit the effectiveness of the Vektore results.

That being said, I applaud work in attempting to use digital techn ology to make existing techniques more effective. I believe that most workers will see theVektore system uses as most applicable after a discovery is made, to gain quicker detailed spatial knowledge.

Alan Carter
2 years ago
Alan Carter 2 years ago

Mineral exploration is the process of finding ores (commercially viable concentrations of minerals) to mine. Mineral exploration is a much more intensive, organized and professional form of mineral prospecting and, though it frequently uses the services of prospecting, the process of mineral exploration on the whole is much more involved.

In a world-first collaboration of mineral explorers, drillers, government and research institutes, today the Deep Exploration Technologies Cooperative Research Centre (DET CRC), the Geological Survey of South Australia (GSSA, Department of State Development), mineral explorers Minotaur Exploration and Kingston Resources and drilling company Boart Longyear signed agreements to collaborate on a Mineral Systems Drilling Program (MSDP).

Aware of the fact that mineral exploration through diamond drilling is costly adventures, not quite sure at the outset of the success ratio, primary dependance of the unseen underground state of mineral deposits have to be ascertained only with this mechanism.

Exploration is termed either Greenfields or Brownfields depending on the extent to which previous exploration has been conducted on the tenements in question. Greenfields alludes to unspoilt grass, and brownfields to that which has been trodden on repeatedly. While loosely defined, the general meaning of brownfields exploration is that which is conducted within geological terrain within close proximity to known ore deposits. Greenfields are the remainder.

Greenfields exploration has a lower strike rate, because the geology is poorly understood at the conception of an exploration program but the rewards are greater because it is easier to find the biggest deposit in an area earlier, and it is only with more effort that the smaller satellite deposits are found. Brownfields exploration is less risky, as the geology is better understood and exploration methodology is well known, but since most large deposits are already found the rewards are incrementally less.

John Koenig
2 years ago
John Koenig 2 years ago

Indeed, XYZGV is a strong predictor of ore continuity and shape, I have many cases in which it was applied with success. Therefore, I have no doubt that this is the path to follow in exploration of mineral targets.

I understand your point about core orientation, it still finds resistance in our industry. Granted, core-orientation is not new; nevertheless, we have come a long way from the spear and methods alike. Modern core-orientation tools are used at the drilling time and they require little intervention from drillers. They are far more reliable than the old counterparts. As such, the orientation of the core is recovered as the core is taken out of the borehole. This new wave of core-orientation tools started with the BallMark and Leslie Anderson (his inventor – patent published in 2000) and many followed his path. The overhead cost of using such tools is relatively small and the benefits are remarkable, provided they are properly used and with proper QAQC is in place. Training and best practices are required. The industry needs to learn more about these techniques and this is the reason why I am publishing on this subject. I am sure that sooner than later it will be the norm in our industry and this is the goal.
Regarding your comments about the use of televiewer probes and log interpretation,I certainly agree with you, it has particular benefits and uses. Both, televiewer and core-orientation tools should be used more often and together as part of a structural vectoring strategy; that is, aiming at acquiring key structural data to (re-)direct drilling. However, each tool has its applications and limitations and an experienced geologist should be consulted on this matter.
So, collecting oriented core or televiewer images from boreholes are basic requirements for the XYZGV approach. However, we are not done yet. The geologists must quickly find and identify the mineralization-related structures, their spatial distribution and vectoring features to allow for an effective structural vectoring. Then, and only then, the geologist should be able to direct drilling towards the mineral body.
Managing the budget to allow for such services to take place is the most critical hurdle, since all the other ones are technical in nature and have been addressed. The exploration leader is the one paying the bills and deciding what to do and when. Services that are standard in the industry tend to be placed ahead of the queue; and the best argument to defend such services would be to include show-and-tell case studies that have been successful because of such strategies. It should provide sufficient argument to overcome immediateness so common in our industry. In the end, it is all about learning.

I understand your frustration and I agree 100%. Committing to a drilling collar and drilling vector on a mineral target is definitively an intimidating task. It is intrinsically more difficult if the geometry of the mineralization is complex. Resolving drilling geometries to find out the shape and orientation of a mineral body by exhaustive drilling should not be considered. This is random walk and it is very ineffective and expensive. In such cases, we would be equalizing a drilling rig to a geologist compass, which is a very expensive trade.
Yes, by using the XYZGV approach referred in the article, we should be able to improve our work and define better collars and drilling vectors to more effectively intersect our targets - the XYZGV approach allow us to do just that. I have been using it for many years with significant success – that is, intersecting and/or directing drilling towards mineral bodies.

I agree that core-orienting tools used in the past were difficult to handle, had many disadvantages and prone to considerable errors. In addition, they would impose considerable delays on the drilling time. Modern core-orienting tools, the ones that work attached to the core barrel assembly (drilling time), are reasonably cheap. Depending on the drill rig set up, the down time associated to the use of the orienting tools can be significantly minimized. This is where workflow management is critical. Currently, a few thousand dollars would rent one kit with two tools for a month and you can run around the clock. 

I definitively agree that there are limitations associated with the use of core-orienting tool; however, they can be systematically overcome by proper use of best practices and QAQC. As for any tool or method we use in exploration, it is critical that a QAQC program be implemented from drilling to core shack and beyond. Structural inferences are derived from the resultant dataset.

Indeed, the XYZGV approach is mostly applicable when a discovery is made; however, drilling with this approach in mind, from the first borehole and on, is very important since we cannot predict when a mineral intersection will take place. In addition, the use of oriented core associated with structural analysis will allow for a much better understanding of the structural architecture of the mineral target and likely reduce drilling before hitting the mineral body.

Thank you very much for the opportunity to clarify some of the questions associated with this subject.

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