and I ask Mr. Merks to revise his web-site accordingly as a question of
scientific honesty.
So do I.
I do congratulate you Gerald for your excellent analyses of the mixed up JW
jargon.
The only time I attended a talk by Mr Merks, apart from being quite ashamed
that a speaker can use that sort of language, I have understood that he did
not know anything about geology, ore continuity, and that he had no
experience in orebody modeling and evaluation. The bases of his resonning
were wrong at the very beginning. May be not for a metallurgist who knows
ore once it has been reduced into powder, but a geologist could not let
him go any further.
We have years of orebody estimations and mining reconciliations using many
of the tools that geostat made available. We practiced variograms from drill
hole samplies to sampling on conveyors, years before it even got mentioned
in published litterature. We have lived with the evolution of the
techniques, and thanks to all the scientists that have worked in many
different fields and universities throughout the world (of course not only
Fontainebleau and Stanford), thanks to generations of practitioners that
have participated and made possible the software revolution that occured in
the last ten years. To day we have more tools, more models to adapt to the
nature of the problems. Not one deposit is strictly identical to the next,
many assumptions are made necessarily, and it is important to choose among
available geostatistical methods the most appropriate one. Of course this is
not enough.. .Practisicing geostat is a professional job.
We of course experienced cases where results were not as good as expected.
Coming back in details, we always managed to understand what we did wrong.
It never came to my mind that Professor Matheron et al. should be held
responsible for my mistakes.Well sometimes yes I pested against software,
bugs in, bugs out, this is another story. I have never thought either that
there was a miraculous mandarin able to deliver a magic formula to solve my
problem, this was my job.
Reprocessing the data differently and finding out where we missed the point,
that is the way to go. That is also what geostat and the software that exist
enables us to do. We all know that in basic geostat there are the
possibility to analyse the data à priori and to tell when there is something
obviously wrong in the geological interpretation, or in the drilling grid,
or in the compositing or overall not enough information. to go ahead. Once
we decide that we can continue, before using a method, there are other
simple variographic tests that can be done to see if we are within the frame
of that given method. And we can find many cases where things worked well
even if we were not strictly within the strict conditions of the model we
used. Kriging has to be done carefully; there are rules and there are means
to test the effect of the model, the neighborhood. We were mining; it means
that we were piking up what we estimated, no place for litterature. I am not
talking of test on two drill holes on an Excel spread sheet§
To come back to BreX, had Mr Merks querried to know if basic geostat tools
were used? Nothing like what I thought I could decipher in his Excell
spreadsheets under variograms...I mean test by a competent person. The
answer is no.
Henri Sanguinetti
- Original Message -
From: Gerald van den Boogaart [EMAIL PROTECTED]
To: JW [EMAIL PROTECTED]; ai-geostats@jrc.it
Sent: Friday, July 21, 2006 9:38 AM
Subject: Re: AI-GEOSTATS: KWBP Test Program
Dear List,
Finally, ...
On 20. Juli 2006 17:54 wrote JW Merks:
Hello Readers,
More talk and not test. I want to know what the KWBP methodology does
with
the Bre-X data. Is that too much to ask?
Kind regards,
Jan W Merks
Let us get some reality into the Bre-X example Mr. Merks insists on to
blame
geostats:
I googled to get some information apart from the things Mr. Merks told us
and
on the first page http://geology.about.com/cs/mineralogy/a/aa042097.htm I
found useful background:
All drillings done after that in the first dataset showed neglectable
amounts
of gold. So if the first drillings done by the original owner showed much
gold and the later drillings showed no gold, we might have one of two
situations:
Either we had extremly bad/good luck in the first drillings or somebody
cheated and gave bogus measurments. Any significance test (e.g.
Fisher-Exact-Test to keep things simple) would suggest fraud.
And indeed fraud of that type was suggest by other evidence:
see http://geology.about.com/cs/mineralogy/a/aa042097.htm
# First, contrary to company statements, Busang core samples had been
prepared for assay in the jungle, not in the testing lab. Videotape made
by
a visitor to the field site showed the humble machines common in assay
labs
—hammer mills, crushers, and sample splitters. Well-labeled sample bags
clearly had finely
