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Gold/Mining/Energy : Canadian Diamond Play Cafi -- Ignore unavailable to you. Want to Upgrade?

To: WillP who wrote (419)	12/20/2002 9:33:25 PM
From: Letmebe Frank	Read Replies (3) \| Respond to of 16206

That's a wonderful list! So now what's missing is the weighting of the 22 factors that agur well statistically for pipe economics. Followed by rating of all the diamond plays in the world against these factors. I'd pay well for THAT information!

To: WillP who wrote (419)	12/20/2002 10:38:42 PM
From: E. Charters	Respond to of 16206

Yeah, that sure is one aspect of the issue. Another is, what exactly is a G-10? # a g10 is by Dawson's definition a pyrope with high chrome and low calcium. It fits a lot of faceted metamorphic garnets. Dawson did not know of the kimberlite/diamond affinity when he made the rule. That is, by what definition. There is a difference, # if you take G10 to be a non faceted subcalcic pyrope then the rule works. Good chemistry is much more than G-10s in any case. # it can be simplified to 15% special types of g10's and low resorbtivity for initial sampling purposes. "The factors that agur well statistically for pipe economics are: (these are biased towards non-eclogitic kimberlite)" 1. pipe being in a regionally low geotherm (<40 mw heat radiation per sq metre). Absolutely. Give me 35 mW/m^2 or less and I'm very excited. # this can be established from the ordinary garnets of the pipe by nickel thermometry. Not many geos know this. Most think you have to find intgergrowth twins in xenoliths. 2. pipe being about ~50+ miles of craton/archon edge, or in euogeosyncline. I'm curious about position relative to cratons, but I'm not able to make any definitive conclusions at this stage. You're not alone in the belief however. # this is the actual distribution in South Africa. The good pipes are near the edge not the centre of the craton, but not too near. 3. large size of pipe. Another interesting one, if you're suggesting the largest ones within a cluster have the best grades. There's some minor correlation between size and grade perhaps. # I am not saying there is a grade correlation, but if there is grade, economics are better if the pipe is large. In fact most mines are large pipes and the Williams was very large. Given size, grade can come down so size is very desirable. 4. other economic pipes being in proximity Big time. Absolutely. I'm a big fan of this one. # look for mines near mines. cluster effect makes sense in many minerals. 6. tendency for pipe to be crater or at least diatreme facies at surface. Yes, in most circumstances. I used to firmly believe this, although I have wavered just a wee bit of late. # Russian pipes are frequently not diatreme facies as are many in far Northern Ontario. NWT pipes are mostly diatreme facies, as are the Kirkland Lake pipes, which incidentally have the highest hit rate in the world for diamond incidence (KL pipes). 8. low oxygen fugacity of pipe (low diamond resorbtion on ascent). Yes, among other indicators of low resorbtion. # Indicators of low resorbtion are fe oxide ratios in olivine, (cheap test) clarity of diamond surfaces, low roundedness of diamond surface planes. Also alteration degree of olivine, degree of reaction rims in garnets and mica etc.. Lack of microdiamonds incdicates possible high resorbtivity. The Diavik has very low resorbtion. You know this because it has lots of micros, very fine clear surfaces on diamonds, a fresh bright green appearance, and sharp edged flat plane diamonds. Never mind their figures, half the published data was lies by DeBeers planted geologists and consultants so they could do a takeover. MPV and Winspear was taken over by the incredible bull headed stupidity and cupidity of management in not being more agressive and candid about the quality of their pipes to the general investor. I believe this is because they simply did not know and had not basic instincts. Long trained not to think for themeselves, they had not capacity when it became necessary in a new field. 9. tendency of pipe to form large diamonds. Yes, if you're referring to the size distribution of the stones. The coarser the better. Of course, if you know that, you pretty much know the answer. 11. copious micro diamond content (rough indicator and lack thereof does not rule anything out). No. Well, sort of. OK, yes, there is a positive correlation between micros and grade, but it's very misleading in many cases if you ignore the size distribution. # There is no correlation between micros and absolute grade, but there is a correlation between condition of micros, and amount thereof -- and resorbtivity to a degree, although some micros probably form during ascent and are not true 3.8 billion year old diamonds. 16. presence of huge macrocrysts. I think so. # gigantocryst are very good to see. See them often in SA mines, but rarely in productive pipes. Especially 4 inch garnets. Got to come from eclogite. Strangely the chemistry is not at all like the small pyrope and generally they are faceted. 10. highly serpentinized olivine. Hmmm. I haven't even tried this one. # deeper the pipe, the more altered usually. 22. high quality of diamonds found. At what stage? Determining "quality" of micros is meaningless. If the quality at mini-bulk stage is good, you already know the answer. ;-) # If the diamonds you see are very good quality at first test, then yes the chances for high value gems is better, and the resorbitivity is low. Was there just one play that got misleading numbers by using X-Ray sortex only? I can think of two, I believe. # Lots got tested with sortex, only one field got tested very early with only sortex and a small sample, and the people doing it had no experience. It is also true that all phases of a pipe must be tested. In many cases only one or two phases are economic grade. The fields is supposed to be low grade but the hit rate of diamonds to kimb was stupendous. The K's all came to surface were the size of football fields and had fair grade even by the primitive plant. (7 cts /100 tons) What this tells me is that there is a diamond mine there, as there is no such thing as a fields with just one type of chemistry and no such thing as a diamond from a poor chemistry entirely. 90% of the Kimberly field in SA is very bad chemistry or alnoite. A lot of totally barren pipes. To judge a field by one or two pipes can be wrong in some cases. In others, trends that are barren could be very instructive. It all depends on patterns and what variance you find.