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Friday, April 13, 2018

Pretium - Brucejack, the little mine that couldn't

The market loved Pretium's Q1, 2018 production figures (link).....for a day (lol)

Ramping down the shareprice
Why? Was there another another spectacular miss on grade.....again?

(looks through notes) - ohhh, juts missed by a mere 5.4 g/t or 35%.

But good news everyone, we've managed to miss out planned head grades every single month in the quarter. At best, they only missed by 4 g/t.

Don't panic

Now that we have 9 months of production figures, lets us look at the ramp up!


Ramp up went smoothly, they reached and exceeded plant capacity within 3 months.

They are milling consistently 5-10% more than planned. Good job guys.


Spot on!

and now it gets interesting....


Consistently bad, typically missing by a third, and this has a knock-on effect


So the difference in actual and projected (from the PEA) gold production is a measly:

~150,000 ounces

I know that some people think that the PEA isn't useful for anything, except when you need $811M to build a mine, or another way to put it:

They have been so efficient, they've decided to mine the material planned for years 16 and 17, to save the good stuff 'til last.

Another way to put it is, if they continue at the same level (head grade, mill throughput and recovery) for Q2, 2018, Pretium will have achieved the impossible normal*, they will have:

  • mined and processed 25% more ore and produced 25% less gold than outlined in the PEA

For that, I think you should get this:

The Sidam Touch

Personally, I can't wait to see the financials next month and the updated Mineral resource update in the fall.

If you've got this far, I have a mathematical challenge for you:

Get the numbers to work?

When I try it, I get Au production = 74,051.4 ounces, a difference of 1,338 ounces.

Or, to produce 75,689 ounces the head-grade needs to increase to 9.3 g/t Au or the recoveries to 99%.

*unfortunately, missing production targets is quite normal for mining companies.


  1. What are your thoughts on Marathon Gold? PEA due in next month or 2.

    1. Assuming their resource model is accurate they are worth looking at. A PEA is an important milestone but still a long ways away from steady state production. Lots of risks remaining in the project plan.

    2. Initial review (skimming the presentation), at the moment the open pit resource is a bit small and the underground grade is a bit low.

  2. Likely just the effect of rounding, as grades and recoveries are listed to one decimal place only, while the mine records would never have done that. Come on good grief!!

    However, what do I know as Otto referred to my comments as about "the most stupid thing I've seen written about mining in years". So was Otto correct on Wednesday morning, or was I much more correct. I was right all along, I think...

    The shares pulled back because the technical chart pattern was overbought, and the concerns in the middle east relaxed, not due to people reading better, I think...

    Regards, Paths, Stockhouse id.

    1. The likely effects of a rounding error? 150,000oz? $195,000,000? Never mind what Otto thinks, you’re a fucking moron.

    2. I knew that was the case, the bombing of Syria had the butterfly effect on the Brucejack mined grades. Those Arab dickheads ruining another great Canadian mine.

    3. I was answering the "math challenge" mr. Pappa, was not saying 3 quarters are explained by a rounding error. So you did not even read this brief blog to the end, you did not read the comments in context, and likely would not get it even if you did? Yet you were quick to write an offensive insult, and vulgar as well. Sounds like you should subscribe to Otto's blog, it's only about 30/month, you will fit right in there.

      AG what I was referring to was the chart pattern. The gold chart was overextended, followed by the resolution of the Syria concern, then being bearish for gold, on the next market day. Stocks go up and down day to day on technicals, often just as much or more so than on fundamentals.

      Mr. Pappa, Sayre's law definitely applies to online blog comments. "In any disagreement the intensity of feeling is inversely proportional to the value of the issues at stake." By way of corollary, it adds: "That is why academic politics are so bitter." (because the stakes are so low)

      Back to the challenge. A rounding error can only explain up to 140 oz. Maybe it's because they have to go to the nearest gold pour, they did not end each month with a gold pour at 12:00 am, and cannot measure to a fraction of a bar with certainty, while the tonnes and head grade are known with certainty.


  3. That wasn't much of a rally and neglecting the PoG I think the reason is these boys are very far from in the clear. Pure panic is likely responsible for these improvements in the numbers and that isn't sustainable. The massive large head grade difference is 100% the bottom line bucks variety of pain. If that doesn't improve a body can write that PEA off as fantasy.

    Otto man has zero business slagging anybody here. He should limit his verbal diarrhea to his own ego-stroking blog, not do the furious stoking over other's work that is far superior to his.

  4. Further to 1338 missing ozs. I have the PoG at $1337. I can't see anybody blaming 'rounding' for a missing $ 1.8m.

    1. They explained this difference in the conference call. I think something to do with the streaming agreement, at any rate they gave a reasonable explanation. Paths

  5. Subscription to online bloggers: US $0-30 per month, subscription to Exploration Insights: US $1,680/year, Implied Advice Received: Short Pretium, Short position on $PVG February 2018: $ xx,xxx+,

    The look on readers/subscribers faces on Wednesday morning: Priceless

    Paths, stockhouse
    midpath@resourcepathway twitter

    1. I don't think Exploration Insights ever tells people to short stocks. That's not the way they roll. They have "implied advice" to not buy Pretium, and that has worked out pretty damn well for 6 years running. Paths, maybe if you try real hard one day you can do laundry for Brent Cook, until then please continue to comment on blogs because there simply isn't enough comedy in mining (although Angrygeo is trying real hard to change that).

    2. Exploration Insights must be trying to add comedy as well. Their lengthy report on Pretium was funny. They may not have labelled it as a short rec, but it was certainly used as one. Their report helped put in the pvg bottom. Paths.

    3. PVG bottom? Seems a bit premature to declare that, donchathink?

    4. Not at all, it's a confirmed rock solid uptrend that has set in, and the previous levels of doubt and negativity cannot return as they were.

      Company is making plans to transition to longitudinal longhole, where ore drifting is completed before setting up stope. They are starting to react to the situation with some constructive modifications. It's not a change to the type of selective mining that Tom has been asking for, but it's a small but reasonable step in that direction. Don't tell Tom, or else his ego might inflate after having been the first person to criticize the transverse method online.


    5. Longitudinal is a joke. Tbese guys have no clue how to follow any sort of mineralization. You cannot state that your reserves are based on a probabistic block model and then state you are going to now get selective. Blasthole stoping is not a selective method first off. Secondly if they are now trying to get selective it likely means that their reserves are only 50% of what they state them to be on a tonnage basis and the grades are pulling up 35% short. So you do the math. 0.5 x 0.65 are the actual reserves here in my humble opinion.

    6. I would see it differently. Defining the mineralization better on each level can only help. They are now in the process of figuring out what they were doing at first was not the best way to go, and so they are adapting. Much better than refusing to adapt.

      No reason why one cannot have a larger scale block model that later gets more selective, with a more detailed more accurate block model made later when easy access makes more information more easily obtainable. Many open pit mines start with a large scale model, then refine with additional holes drilled from each bench. The company is serious about following good geostatistics procedures, that is very correct, and once they continue in that direction, it will improve the results.

      I will accept that if the block modelling was all perfectly ok, then the mine would not have had issues to the extent seen, and yes I have had some doubts about the grade "as defined by the block model" all along, and more so in recent months. However, that does not necessarily mean the mine does not have a positive future, or that investment returns will not be between acceptable to very good. Clearly the block model is not a long way off, since the mine started up reasonably well.

      It's just that the highest grades have very small ranges, and without close spaced drilling there will be no indication to confirm the high grades as specifically located. The methods they want to use will not be accurate enough unless they do get the density everywhere. A little less reserves, and some additional difficulty getting their grades, I'll grant you that maybe, but the five mineralized lenses are large enough to suggest they will have more than enough tonnage, if they do lose some here.

      I think they can modify longhole into a somewhat selective method since they use remote scoops that can remove all ore before a waste grade set of rings is blasted, etc. I don't know for certain first hand, as my mining experience was mostly either in shrinkage stopes or exploration and developing projects that were not yet in production.

      I doubt that I can get anywhere trying to sway you Doug, as I see you as the most knowledgeable PVG bear online. However, for myself and others, the crux of this whole mine, (with crux defined as the most difficult part of a problem to solve), is seeing the issues in a reasonable way. There are some issues and problems that investors can identify. That should not translate into some people wanting to be short the shares. These are issues that are already more than accounted for in the share price, and then some. These are issues that are manageable, with some solutions being implemented, and other solutions available if need be for later.

      Regards, Paths/midpath

    7. Paths you must be in deep here. I feel sorry for you. Your last post started out like Mary Poppns but then deteriorated into Julie Andews and the Sound of Music. You need to do a gut check.

    8. I seem to be the only retired mining engineer who has a supportive, overall bullish viewpoint about this company and the shares. It concerns me that I seem to be very isolated, being about the only person giving technical reasons for optimism.

      I have stopped to do a gut check several times. If I read too many negative comments, I can have doubts until I reconsider everything in context as part of the big picture, then the doubts go away in a few seconds.

      I have a good track record for my comments on this. In late December, I explained that the shares were vulnerable, and in response to a direct question from one person, I suggested the possibility of buying puts to cover a long position. When shares fell to a reasonable support, I explained the 6.85 us level may not hold, that was correct. I called a bottom at about 6.6 us, that was correct. I did agree the grade will be coming in lower and gave rough probability estimates for various grades. I listed about a dozen errors in the exploration insight article, which so far remain as overall correct and reasonable comments. I expressed some optimism and moderately positive expectations for a reasonable Q1 update which was correct. So I have been getting this right, in many instances. I have been making correct calls on what will happen, and posting them before they happened on Sstockhouse. If my perceptions were wrong, I should have been posting incorrect comments. no?

      I made a mistake, yes. I thought the bounce in share price on the update would hold and follow through. Obviously that was wrong, or at least premature, delayed a while.

      All things considered, I think that I have been correct and reasonable over time, maybe more so than any other person on the planet who has taken the time to write online comments about PVG. The common thread I see is that every single person who has expressed a profoundly negative opinion about this mine, has either given no explanation to back it up, or they have given an explanation that can be shown to be faulty or outright incorrect on one or more technical reasons.

      Paths, stockhouse, midpath twitter

    9. D.B., Over a year ago you mentioned looking at cross sections (on I tried to find the cross sections you referred to. I looked through documents on sedar, all I could find was the few sections included in the technical reports. Do you have a link for pvg cross sections? Thanks. Paths/midpath

  6. How is that prediction of follow through going Paths?

    Like 15% down...

    That was really a great call!!

    And the candle in the weekly chart is absolutely promising!!

    If anyone bought PVG following your advice I'm sure he/she will be today extremely happy...

    1. I don't make predictions, I sometimes make a projection based on reasonable analysis. Yes I figured that wrong, you can say it was a wrong call, gold made an extended topping tail, on the same day as trapped short sellers were surprised by the update, and I was away, and mid east tensions calmed the following day. This was after I had accumulated a record of many correct calls made and posted in advance, has anybody else following pvg done that? How many times has the gold price banged against the 1370 door? How many times might it have to bang against it to break the door down to the upside? (hint see the old charts, try some technical analysis.)

      As for Tom's message, exploration insights made information that had obvious appeal to short sellers. They publicly released a long report full of technical mistakes. I forwarded a list of all their mistakes to their twitter account, no reply. They missed the bottom, they helped form the bottom, and there is no excuse for them to have published a report loaded with obvious mistakes.

      Paths, stockhouse.

    2. Paths, You don't even have the courage to reveal your name so I think we can safely discount your "list of all their mistakes" especially as you seem to think nobody else known anything about mining.

  7. Please note that at some point Pretium is likely going to try simply producing for a whole quarter from only the high grade stopes, and that quarter will have some pretty nice numbers. Of course they won't do a grade reconciliation to reveal the "high grading". Somebody mentioned an updated resource. Don't expect too much from that, it will be done by Warwick Board (a company employee) and at best rubber stamped by a consulting firm that is being paid very well to concur.

    1. Large underground mines are usually locked into a mining sequence that precludes high grading. The sequence would be established early in the mine life and no geotechnical consultant would recommend otherwise, nor would a company be likely to deviate from it to any great degree because it would jeopardize future mining activity. That said, any mine plan will be flexible enough to allow stopes to come on line earlier or later. This is because the development required to bring them online may be delayed (for many reasons) and yet guidance is still the yardstick to be met.

    2. Bill, that is simply wrong. Once they open sufficient stopes, they can change the sequence whichever way they want. Yes there are consequences, for example they may sterilize some resource blocks. But they absolutely can (and should) develop and mine the high grade stopes first, and if they want to blend, they should DEFINITELY blend from lower grade stopes with a HIGH degree of confidence (i.e. the West Zone). It's very very simple (as a plan, obviously much harder to execute but that's an inherent quality of underground mining).

    3. If you say so Tom. I guess my 45+ years in the business were wasted, and I never suggested they shouldn't begin mining in higher grade areas. Bringing grade forward is a classic approach to improving NPV but there are both practical limits and engineering limits to high grading. If you understand geomechanics you will know what I mean. And yes, I'm an engineer who understands geomechanics. I don't know anyone who will screw up an entire mine to have a good quarter.

    4. Of course there are practical limits, nobody is saying they can just mine whatever grade they want. They have already *publicly* revised the mine plan to have up to 12 stopes (up from 6) in production at any one time. That gives them added flexibility to chase grades without sterilizing so much future production. What I'm saying is that they are possibly, if not yet then soon, going to be revising the mine plan even further but *privately* (without disclosures, at least for a while) in order to exploit even more of the high grade stopes. As for screwing up the entire mine, I certainly don't think they can do that in one quarter. As to 45+ years in the business, you'd think you would have learned to read the technical reports before giving your opinion.

    5. "Once they open sufficient stopes, they can change the sequence whichever way they want."

      Now let's see...we have Tom and his opinion above suggesting we should mine all over where the grade is highest and we have the company mining engineers saying something different. Who should we believe?

      Since it's not obvious to you Tom, I am commenting on AG's analysis and on the news release. If you want an opinion on the technical reports you will have to pay me, just as others do.

      The market benchmark for Q1 results is Pretium's guidance issued early this year. They met their guidance, although they were on the low end.

    6. I think the biggest concern is what will happen to the head grade once the mill is increased to 3800 tpd? Will they be able to keep it at ~9 g/t or will be see a decrease to <8 g/t due to increase dilution by needing to use less selective mining methods?

  8. I know some companies count blasted rock as production and others sell oz forward to be delivered 3 days later when poured and hope when audit annual it balances.
    I have seen a 10,000 year end adjustment on oz sold forward followed by 800 mil capex write down in next 18 months . Just to get the year end bonus and options.

    1. Not public companies who follow IFRS rules. Metal sold forward would show up on the balance sheet and changes in metal value from one AP to another would appear as unrealized gains or losses on the revenue statement. Note that there is a difference between metal produced and metal sold. The two numbers are almost never the same, although the difference narrows over the course of time.

    2. That is what I was thinking about the 1338 oz shortfall, it was due to some high-grade material mining at the end of December 2017 but processed in Jan 2018.

  9. I think it was clear after the first six months that they had a reconciliation issue and this quarter is no different. And yes, it IS unfair to compare to a PEA. PEA's are not used for financing, unless the banker is crazy. The comparison should be to their guidance, and by that one they met it, although on the very low end of the 150k to 200k oz they published in January. From what I read they have two issues. First is understanding the grade distribution, which is extremely erratic and does not seem to follow normal statistical models. I don't know any other mine where they have to drill on 5 meter centers to estimate grade. Second issue sounds like development is behind schedule, hence their announcement that they intend to accelerate to 700 meters per month. It will take a few months but this should give them better flexibility in the future, although their costs will be higher in the short term. Overall I think this will be a hit and miss mine for its entire life, although there are things they can do and seem to be doing to improve.

    1. The grade at VOK is not based on a PEA, it is based on a Definitive Feasibility Study. They have a block model and everything. The mine was financed on the basis of that block model. Now it is not working so it is a big deal. Their revised guidance is prima facie evidence of that. And now with three crap quarters of production, if they come up with a few good ones, we won't know if it is because they are high grading or the block model is correct after all, UNLESS THEY DO A GRADE RECONCILIATION.

    2. No need to shout Tom. I can read well enough. I believe AG said in the write-up that this work was based on a PEA. I haven't looked at any of the technical reports so I'll leave that alone. Yes, the mine was financed based on a resource/reserve model but anyone who knows the history of this deposit should be aware that it had reconciliation issues going back to test mining. Time will tell if the model eventually reconciles more closely. A mere 9 months is nowhere near enough time to definitively say so. The fact that they're tightening their drilling suggests to me that they're working on the issue.

    3. You haven't read the technical reports yet you are commenting ... shaking my head, Bill. Tightening the drilling will get them to a certain point. But they are still bulk mining 15 meter x 30 meter stopes via long hole. And that may simply be much too large. I don't even need grade reconciliation to tell me that, I was able to create simple mining shapes from their drill plans. I think even a barely competent geostatistician would be able to take the raw data (in areas with tight drill spacing) and put together a mine plan, the only problem is that it would be selective mining with little if any use for long hole.

    4. I am commenting on this review and on their news report Tom. I thought that was obvious from what I wrote. Geostatisticians don't do mine plans. (Shaking my head.) That's the job of mining engineers.

    5. I'm adding to my reply after re-reading your post Tom. You may well be correct that they have a dilution issue along with their grade issue. But there is no information provided to differentiate the two. You seem to think that longhole mining is incorrect for this deposit. Maybe so but I would guess they have a few experienced people advising them on that issue. I know I would if that was an issue at my mine. The company appears to be shifting from using their reserve model (normally used for life of mine planning) to a more appropriate ore control model in areas where mining is intended in the near term. This approach is commonly used in most mines, particularly in open pit mines where resource model block size is much larger and search radii are much larger. No surprise there, except they seem to be drilling on 3.75 meter centers, which is quite tight, even for a gold mine. Nevertheless, a tighter drill pattern will only get them a better estimate of grades. It won't get them any more gold in the rock. From this perspective the resource model used to estimate reserves may have been too optimistic.

    6. "Geostatisticians don't do mine plans. (Shaking my head.) That's the job of mining engineers." I was using "mine plan" generically and geostatistician is a skill set not a person. Who do you think designed the mine plan at VOK?

    7. Tom, your ignorance of mine design and mine planning is obvious. If you had read those technical reports that caused you to shake your head you would know how geostatistics was used to develop the resource model and then how mining engineers developed the reserves along with the mine design and mine plan. I leave it to you to read the reports to learn. Oh, and geostatistics is a skill set. A geostatistician is a person who possesses the skill set.

    8. I'll leave you to engage in semantics, and should the disaster unfold at VOK as I suspect will occur (over several years, admittedly) then we can discuss again who exactly thought up the mine design and mine plan for Pretium (hint: it was top-down not bottom-up, the same style used so successfully at Pirquitas).

    9. My mistake, I used the 2014 Feasibility Study as the technical report supporting the updated reserves (Dec 2016) doesn't appear to have been released.

    10. Semantics are important. They tend to show who knows what they're talking about. But, here are the answers.

      Resource estimate was done by Snowden. They are very good at geostatistics...among the best. If I had any criticism of them it would be that they may be overly technical and not as strong on geology. But...I have very high regard for them overall.

      Reserves and mine plan were done by AMC. They are also very good. I can't think of anyone better.

      Back to the statistics...From P 104 of the Jones report here are the composite stats: (Apologies for the bad format)

      Statistic Gold g/t Silver g/t
      Samples 79,699 79,699
      Minimum 0.00 0.25
      Maximum 16,552 9,383
      Mean 2.57 8.59
      Standard deviation 69.54 41.94
      CV 27.03 4.88
      Variance 4,836 1,759
      Skewness 109.40 70.11

      To me the notable ones are the coefficient of variation (CV) which is over 27 for gold. This indicates huge risk in trying to properly estimate grade.

      The other notable one to me is the skewness...over 109. These are very high compared to what I normally see and indicate that this deposit doesn't easily conform to statistical analysis. The log probability plot (P 105) should be a straight line if the composite distribution is log normal. But the line isn't straight, which means the distribution isn't log normal. To me that means one of two things...either the grade interpolation is going to be hit or miss....or the geo needs to be one of the best there ever was.

      Lastly...look at the mean gold grade of 2.57. Just a gut feel here but that's awfully low as an average grade for such a high grade deposit. It means that huge amounts of the deposit are essentially waste and only very small amount would be ore, and they would likely be widely spaced among all the waste.

      As I see it the main problem they have is a deposit that doesn't conform to normal statistical analysis. In essence I think that's what Strathcona Minerals said during the test sample when they said there was no resource. They didn't mean there was no gold...only no way to estimate the resource. This is probably the main reason why the deposit has not yet reconciled closely to expected grades. Drilling it on 3.75 meter intervals will help eliminate more of the waste, but it will likely also convert some of what they currently call reserves into waste. How much? I have no idea, but I suspect there will be a new reserve report coming out in a year or so.

    11. Bill I appreciate that upon further prodding you took it upon yourself to review the data. You are correct as to the identity of the consulting firms who did the technical work. They weren't the ones who came up with the brilliant "plan" though. It was Warwick Board (formerly of Snowden), Kenneth McNaughton and Robert Quartermain.

      A bio of Dr. Board states the following:

      "He was most recently Senior Resource Geologist at Silver Standard Resources Inc., where he was involved with the structural assessment and initial non-linear resource modeling of the high grade gold mineralization at the Brucejack Deposit. Prior to Silver Standard, he was Principal Consultant at Snowden Mining Industry Consultants Inc."

      You see, the plan was hatched all the way back in 2011-2012. Before the infill drilling, before the bulk sample. Before the technical work by Snowden and AMC.

      In any case, you are generally correct about the statistics.

      They did use MIK for the high grades which technically will help create blocks and consequently mining shapes that encapsulate those high grades. The problem is that MIK will also excessively smooth the cutoff boundary. So you end up with an uncapped resource model that accounts for nugget effect but at the expense of having a rather (too) low resolution. There may be as many ounces of gold in VOK as stated in the resource tables, but it is unlikely to be recovered at the stated grade, or the projected cost, based on the MIK block model.

      And as a bonus for reading this far, I'll even share one of the "secret" indications that they are slowly coming back down to Earth at Pretium (even if they aren't admitting it). The mining method in the DFS calls for full width slashing in preparation for long hole production in the stopes. But curiously Pretium has been talking about blast "rings" and even illustrating blast rings drilled in a fan pattern from a cross-cut (not parallel blast holes from a full width slash). Importantly, the reason for full width slashing is stated as follows in the DFS:

      "Full width slashing will permit parallel production hole drilling across the entire width of the stope, and will reduce the potential for ore in stope corners to fail to break to design due to inadequate free face or poor explosives distribution. Ore recovery will be higher than a fan drilling alternative (in the absence of full-width slashing). Given the significant value of Brucejack ore, high recovery was an overriding criterion in the design."

      So apparently they are not concerned about "high recovery", and the very likely reason for that is their stope shapes are already too large. Thus they have found that a ring pattern will actually work better because it has made the most important contribution possible : the reduction of waste going to the mill. Of course this is just a small step away from long hole bulk mining toward selective mining at VOK, but it is an increment nonetheless.

    12. I only read the sections on how they calculated the resource so that I could get some handle on possible reasons for the poor reconciliation.

      MIK has become popular, particularly in Australia, which is the location of the origins of Snowden. It may be useful for deposits like VOK where normal statistical methods don't seem to work. The downside is that it will reduce tonnes and increase grade in almost all cases where it's used for resource estimates, and the grade aspect appears to be manifesting itself with VOK. There is an interesting paper by a mining engineer, J Poniewierski on the subject. I only have experience with one property where the grade was about 20% higher using MIK vs OK. Interestingly the total metal was about the same.

      For primary stopes complete overcutting and undercutting is preferred for reduced dilution and improved fragmentation, but the downside is more work for development crews. Since Pretium has increased their development footage this may be the reason they went to ring drilling....they are behind with development and want to take some of the pressure off that activity. Secondary/tertiary stopes are more difficult to mine and some ring drilling is always necessary. It's very important to not allow secondary stopes to fall out of sequence because they will become unmineable due to stress failure. If primary stopes are properly backfilled then ring drilling in secondarys should not be a problem.

      Finally, the other potential issue at Pretium is their mining rate. Their stated intentions to increase the rate may be too aggressive for the size of the orebody, particularly if they wind up downsizing their reserves as I think they will eventually wind up doing. The usual result of a too high mining rate is higher dilution as mine managers strive to fill the mill.

    13. These guys also used MIK at Pirquitas. It didn't go so well until they finally got into the sulfides deeper in the deposit below the oxide/transitional boundary. Unfortunately at that point they were near the end of the open pit mine life. You see a similar problem with Nevsun at Bisha where the boundary zone between primary and secondary copper sulfides was inadequately defined using Snowden's kriging software. The issue is mainly the modeling based on geostatistics with little regard for extraction/processing considerations resulting in a fantasy mine plan.

      Back to Pretium and VOK, they are simply mining too large an envelope around the high grades because they assume a gradational boundary in establishing a statistical cutoff whereas in reality there is a very sharp spatial boundary between the high grade veinlet swarms and low grade stockworks. If they used gram-meter or similarly-derived mining shapes, this would guide the optimal constraints for each zone. Low grade values should be set at zero, and the cutoff is determined indirectly by the volume of dilution (waste and low grade ore) required to mine a particular shape. One way to optimize decisions under this approach would be conditional simulation.

      There is much validity to your point about secondary stopes especially in larger panels and with poorer ground conditions. I would point out, however, that early in the mine life they are going to be almost 100% in primary stopes. As for taking pressure off development, that's an interesting hypothesis with problems of its own. I'm not convinced it would help get more targeted production to the mill. I guess if you are simply trying to keep the mill filled, then it could be a band-aid. That said, I think the fan drilling is likely an early nod toward the more selective mining that their grade control plan implementation already contemplated (blast hole sampling clearly suggests a reduced stope footprint). But I wonder if this isn't robbing Peter to pay Paul as the secondary stopes will have to deal with variable thickness remnant pillars and sills in the primary stopes. Future production would be less predictable with problems from overbreak, underbreak and sloughing between blast rounds. Tonnage for sure would be reduced, but not sure how much grade will improve.

  10. I've updated my poop and the latest presentation came out last week. It's a semi-insulting read for anybody who's followed this story.

    "Some minor grade management issues are being addressed"
    "Lots of visible gold in the workings"
    "Geological mapping completed to a high standard"
    "Grade control is a data-driven and iterative process"

    Snowden Mining Industry Consultants Pty Ltd. seem to be the flaming retards.

  11. The most sophisticated and successful professional mining investor to whom I have access makes the point that ​for 4Q17 and Jan/Feb18 PVG's grade reconciliation process was not working well. Based on that, this analysis is too heavily weighted towards something that has been fixed and improved.
    I am not a robot. :-)

  12. Looking forward to seeing how the next hi grade world class under ground gold/silver mine performs compared to PVG. Should be very interesting to see if Continental's FS projections meet/exceed or are less than mining reality. The one thing I like about Continental is the small pilot mining operation they have been running for quite a while to compare actual mining grade to FS grade numbers.

    1. Bingo! That is what you do, with an u/g deposit that has high grade. You test mine it for quite a bit so you can figure out what's there. You start a smaller scale operation and then expand once you know the correct parameters. You certainly don't do what Pretium did.

    2. I plan on loading up with CNL over the next 2 years. Might be a mistake but Newmont buying 19.9% at $4 when the stock was trading at $2.30 was very telling to me. Standstill agreement until CNL in commercial production. Country risk is a concern but then it is in Canada as well for energy/pipelines.

    3. This comment has been removed by the author.


    4. They applied a 36% dilution factor to their reserves, so yes, any results will be of great interest.

    5. Share prices are liable to do what you least expect but it probably won't be a mistake to load up on CNL especially on dips toward $3CAD. That's just too cheap.

    6. I'll have to do something similar with Continental and Dalradian (if it gets built)

    7. Glad to see you have doubts about the Dalradian mine being built - Prince Charles visited the area two weeks ago - Dalradians office was closed and Prince Charles was advised not to shake hands with those linked to Dalradian - the Northern Ireland office are too clever for Dalradians contrived PR stunt

  13. Off topic drilling news from CNL this AM, upbeat news for their block model. Interesting to compare with PVG's approach.CNL are drilling like mad while mine being built. They want as much gold as possible before standstill agreement expires.á-Deposit-at-Buriticá-Colombia.html

    1. Keeping in mind the gold distribution is similarly skewed at both Buritica and VOK but even with good lateral continuity they are still doing much more pre-development validation at Buritica (both in modeling and actual exploration/test-mining). When Continental Gold goes into production, the operational risk should be substantially lower compared to Pretium. I would expect it to get bought out at a strong premium especially if they can upgrade the resources and bring more gold into the long-term mine plan.

    2. I think the issue at Brucejack is that there is extreme high-grade veins, that aren't as prevalent at other deposits - I don't know of many projects (and I'm happy to be corrected) that have drilled veins with >1% Au.

    3. to follow on, appears to have skewed the resources considerably.

    4. The "veins" are not really veins unfortunately. If they were, at least they could build a wireframe along the domains. This is something more complex, akin to what they've encountered at Rubicon's Phoenix deposit in Red Lake, but even more so (Phoenix is at least vein-hosted). The saving grace at VOK is the grade ... it's simply so high that you should be able to mine in several areas despite the complexity. The "model" for finding these "mine" areas is compositing of drill intervals as gram-meters and then connecting them to form reasonable stope shapes. This doesn't work in most of VOK where only a few widespread high grade intercepts inform the resource. It works in portions of VOK drilled tightly where a high frequency of intercepts are clustered. I think it would actually be a worthwhile exercise to take the drill data from Pretium's infill program and use something like Leapfrog to outline these zones. The exercise would be simplified if only intercepts above 20 grams are considered. I've done it very roughly with my 3d model and came up with ~2 million ounces @ +20g/t. This would be at a fairly high confidence level, it could be (much) more but with decreasing level of certainty. Angrygeo care to take a crack with Leapfrog?

  14. I looked for composite stats for Buritica but could not find them in the Nov/11 amended resource update. I was able to find CV stats in the 2014 PEA and they seem quite reasonable at around 2.0. I could not find probability plots so cannot tell if the distribution is normal or log normal. No skewness figures provided either. Based on the lower CV I would hazard a guess the resource estimate has much less variation than VOK. But the studies don't provide good information to judge.

    1. Bill you can find this in the 2015 Mining Associates Technical Report. Uncapped composites range between 0.7 to 8.7 (they actually calculate it for each vein domain). Average of 2.0 seems about right. Outliers (2% of values) were capped to create a hybrid model to reduce the influence of high grades on adjacent blocks. The resource blocks were constrained against wireframe volumes. Test mining has already demonstrated that grades in the block model consistently understate the actual mined grades using long hole (this was also the case for the results of other estimation methods done for comparison). Ari Sussman is really sensitive to screwing up on the resource model, the association with Colossus Minerals in that regard is something he wants to have people forget (which is why he and Vic Wall eventually decided on the long road to production instead of their original "brilliant" plan for Buritica, which would have looked a lot like the one at VOK). So this is the real deal but unfortunately there are other reasons why Continental Gold isn't necessarily the prettiest girl at the fair.

    2. "Continental Gold isn't necessarily the prettiest girl at the fair." Maybe not the prettiest but as long as Newmont proposes when the dance is done in 2020. LOL

    3. I think the proposal is contingent on a clean bill of health with regard to issues like illegal mining (resulting in the deaths of 6 security guards at Buritica last year). Perhaps everything is sparkling by 2020 but it's also possible that a suitor will wait a year or two longer.

  15. VANCOUVER, British Columbia, July 09, 2018 (GLOBE NEWSWIRE) -- Pretium Resources Inc. (TSX:PVG) (NYSE:PVG) (“Pretivm” or the “Company”) is pleased to report second quarter gold production results and provide guidance for the second half of 2018 for the Brucejack Mine.
    Second Quarter 2018 Production Summary
    111,340 ounces of gold produced
    14.9 grams per tonne gold mill feed grade
    97.7% gold recovery rate
    236,990 tonnes of ore milled
    2,604 tonnes per day ore milled
    “With more than 187,000 ounces produced in the first half of 2018, we have delivered on our first half 2018 guidance of 150,000 to 200,000 ounces of gold,” said Pretivm President & CEO Joseph Ovsenek. “The successful integration of our grade control program into our mining process has resulted in increased grade to the mill with production exceeding grade control estimates for the quarter. Brucejack has now achieved steady-state production, and we expect to deliver 200,000 to 220,000 ounces of gold for the second half of 2018.”
    Second Quarter 2018 Monthly Production

    Q2 2018
    Grade control integration and steady state gold production
    Gold production from March throughout the second quarter has reflected the full integration of the operational grade control program which comprises drilling, sampling and local modelling. Grade control is critical for grade prediction and the refinement of stope shapes, which results in reduced dilution and optimized grade to the mill.
    Operational grade control: Infill drilling
    A reverse circulation (“RC”) drill was introduced as part of a trial program to improve the efficiency and productivity of infill drilling. The RC drill has now been demobilized as it did not deliver the expected cost savings or productivity gains. Going forward, the infill drill program will be carried out with diamond drills.
    To improve access and build stope inventory, the rate of underground development was increased to 700 meters per month, up from the 420 meters contemplated in the 2014 Brucejack Feasibility Study. The development rate increase began in January and is expected to remain at an average of 700 meters per month during the duration of stope inventory build-up in 2018.
    With the results of the infill drill program now available for the benefit of short-term stope design, the stope inventory build-up is expected to increase to 10 to 12 stopes during the third quarter. The increased stope inventory will improve the management of production grades.
    Steady State Production – Second Half 2018 Guidance
    Production Guidance
    Gold production at Brucejack for the second half of 2018 is expected in the range of 200,000 ounces to 220,000 ounces, for total 2018 gold production of 387,000 ounces to 407,000 ounces.
    Financial Guidance
    All in sustaining costs1 for the second half of 2018 are expected to range from US$710 per ounce gold sold to US$770 per ounce gold sold. As production has now reached steady state at the Brucejack Mine, an increased focus will be placed on operational efficiency to reduce costs.
    Lyle Morgenthaler, B.A.Sc., P.Eng., Chief Mine Engineer, Pretium Resources Inc. is the Qualified Person (“QP”) responsible for Brucejack Mine development. Warwick Board, Ph.D., P.Geo, Pr.Sci.Nat., Vice President, Geology and Chief Geologist, Pretium Resources Inc. is the QP responsible for the Brucejack Mine grade control program.