<<Claude, so if 2 samples over 25 meters is acceptable and we are very much aware that trenching was the preferred method of choice with this property, it is possible that the criteria was met by GEOLOGIST Paravicini, agree? >>
Well yes if we are talking the "indicated" resource. No as far as the proven are concerned as we need 3 samples within 25 meters for proven.
I have read that 2500 feet of trnenching were performed. That is roughly 700 meters. Well keep that number in mind and read the next answer.
<<Next question. Why would it be as costly as you say to sample this particular piece of property? >>
Lets take the case of the "indicated resource" of some 78 millions ounces of gold:
If we are to follow US standards we must sample so each ounce that we declare as "indicated" is within 25 meters of a sample.
Now, what is the size of an ore block that can contain 78 millions ?
(we gonna asume here that it is one continuous block; obviously we are likley to have much more as there are at least 15 targets on the property, but assumption will work in finding the number of samples needed to respect the standard)
To answer this question we must know the average grade of the deposit. Lets asume here a relatively high grade of 8 gram/ton (some .25 ounces per ton, which is roughly equivalent to 14g/cubic meter at a gravity of 1.8 ton per cubic meter)
So if we have .25 opt per ton, how many tons do we need ? SInce it take 4 tons to have an ounce and our indicated resource is 78 millions ounces, you can conclude that we need 312 millions tons grading .25 opt (8g/t) to obtain 78 millions ounces. In terms of cubic meters, well we need 173 millions cubic meters as each cubic meter has a density of 1.8 and weight 1.8 tons.
Lets use 312 millions tons...or better..lets use 173 millions cubic meters since the spacing between samples is 25 meters.
173 millions meters is a block of ore measuring:
1: 6km (6000 meters) in lenght
2: 1km (1000 meters) in width
3: 29 meters in depth
6000m X 1000m X 29m = 174,000,000 cubic meters or so.
This size of a block seems reasonable as the property is in the other of 1km X 16 km or so. The remaining of the property is at least 2X the block describe above...which would allow for another 157 millions ounces of "inferred". What I am saying here is that the size of MINE's property can support the numbers advance by Guido, ASSUMING:
1) an average grade of 8 g/t
2) continuity on all the property.
SO:
The final question is: How many samples are needed to define a "indicated" resource on a bloc of 173 millions cubic meters ???
Certainly the tough question to answer.
Well lets take the bloc on surface which measures 1000 meters by 6000 meters. Lets asume we take a sample at every 50 meters along the lenght and at every 25 meters along the width. This will ensure that each sample is 25 meters from another sample but not within 25 meters of two samples (actually, one sample will have two samples taken on each side of it at 25 meters, but the key here is that these samples will be on the same section line, so no volume can be computed. Since sections are 50 meters wide, this respect the US standards).
X----X----X----X----X----X----X----X----X----X....(120 samples....
|
X----X----X----X----X----X----X----X----X----X
|
X
|
X
.
.
.
X----X----X----X----..........so on
(40 samples)
So we get 120 samples in the lenght (6000m/50m) and we get 40 samples in the width (1000m/25m). Simply mutiply (120X40) and you get 4800 samples taken on surface or 40 samples per section, each section being 50 meters apart on a lenght of 6000 meters or 6 km.
Now keep in mind that we need to sample the same amount at depth if we want to get our volume of 173M. Multiply your 4800 samples by 2 for a set of samples some 30 meters below surface and you get 9600 samples needed to get the indicated resource of 78 millions ounces.
But the truth is that the US mining standards define the distance of 25 meters between drill holes (not samples). In reality, when assaying a drill hole, one assay is taken at every meter. So if we were to sample the 173 c.m. block, we should assay at each meter down depth, which in our case means 29 times. Then the numbers of samples become 4800 X 29: 139200 samples.
I'let you imagine the number of assay needed to classify the gold as proven. A grid at 25 meters centers is no small thing.
If we now consider the proven (measured) resource of 6M ounces, we need much less tonnage or cubic meters. At the same grade, 13,000,000 cubic meters will do the job... or a block measuring 1000 meters in lenght, 450 meters in width and 29 meters in depth. Such a block would need some 20,000 assays to define it has containing 6M ounces of gold. This is the equivalent of some 700 drill holes to a depth of 30 meters....a program that would cost several millions.
All this is theory of course. And the picture changes a lot if we have high grades pockets of several ounces per ton on the property. It also changes if the continuity is not perfect.
I know for sure that the US standards are not scealed in cement and that many variables could cause a miner to conclude that some ounces are proven even if the rule is not followed by the book. In reality, exploration programs that follow the book are much more expensive and I am sure that in many case, the corners are cut rough. But I also know several companies (Minefinders, Geomaque and others) that are drilling several hundred holes on their property to defince a resource of a few millions ounces. Each of these holes is anywhere between 30 meters and 300 meters deep with dozens and often hundreds of samples per hole.
That is why I am surprised by the conclusions brought by Guido based on 2900 samples and a small (in $$ terms) exploration program. Still, a placer deposit is special type of deposit that is not explored in the same way as others to which the US standards apply. AUger drilling, and bulk samples are used instead of diamond and RC drilling. It is also possible that the technical and historical data available is much more comprehensive that has been said. I don't know.
I hope this helps...even if it is somewhat technical...and probably not completely acurate. For sure, it will stimulate the discussions.
CC
Disclaimer: I never studied an exploration program perform on a placer deposit. So there may be some techiques that I am not aware of which would make Guido's calculations perfectly fine. If such is the case, well I will learn again when I read the detailed report to be published soon.
|
