Your first sentence is long and diminutive to the reader.

He specifically reiterated without support an assertion of a fact I'd addressed specifically, at length, and with considerable real world data. A finer point: I wasn't dismissing him specifically, but his actions. I'm not here to make friends or even particularly to persuade, but to expand my own understanding of a subject I find of absolutely crucial importance. Occasionally I find merits to discussing matters with those holding opposing viewpoints.

Some guy came up with this concept called "Graham's Hierarchy of Disagreement". You should check it out:

http://blog.garrytan.com/grahams-hierarchy-of-disagreement-h...

As to decoupling: I'm not aware of anyone who's specifically looked at GDP/quad data, but I had, using public data (the blog post consists of a set of graphs with links to the original from Wolfram+Alpha), and a bit of commentary. You're welcome to agree or disagree with specifics, though an ad hominem without any other basis for disagreement doesn't do you much credit. You're at levels 2 & 3 of the hierarchy. bcoates managed to attain level 3.

Though as a DDG fan I've got a newfound softness for quacks.

Your first sentence includes a number of terms that demand unpacking.

Which? "Economic decoupling" or "capital depreciation"?

First: yes, this is a complex area, it's got a bit of its own language. That's typical of any advanced field. That said it's not overly complex, though you've got to be willing to take and bin a fair amount of conventional wisdom.

For more on decoupling, associated with resources in general, see:

http://newsroom.unsw.edu.au/news/science-technology/true-raw...

http://www.pnas.org/content/early/2013/08/28/1220362110

https://en.wikipedia.org/wiki/Decoupling

Briefly on peak minerals:

⚫ Exhaustion of any extractive resource follows a curve similar to that M. King Hubbert demostrated for oil in the 1940s and 1950s, accurately predicting US peak production in 1970, and a global peak between 2000 and 2010[1]. Data are a little hazy on global production yet, but it's clearly been flat despite massive increases in market prices and capital expenditures by oil companies. See Shell Oil's profit warning issued just this week. You're welcome to read my take at http://reddit.com/r/dredmorbius or The New York Times, whichever you find less quackish: http://www.nytimes.com/2014/01/18/business/energy-environmen...

⚫ Mining costs increase with falling ore grades. Heinberg cites this OilDrum piece: http://anz.theoildrum.com/node/6974 "As a rule of thumb, when the quality of the ore drops, the amount of energy required to extract the resource rises". The rationale: lower grade means more overburden and tailings to remove -- you've got to mine deeper, or excavate a large area, or filter more seawater, or go through whatever it is that's your source for the mineral.

I'm aware of a few specific lower bounds on ore concentrations. Estimates are that uranium ores must be at least 200ppm for net positive production. See: http://www.stormsmith.nl/i05.html and generally: https://en.wikipedia.org/wiki/Peak_uranium

Leibig's Law is a separate observation to the issue of peak minerals -- it's not describing how or when minerals peak, but what the effect of their peaking is on the remainder of the system. For a critical mineral (say, phosphorus) to peak would have dramatic effects throughout the system. Having enough cobalt or gallium for iPhones won't do much if you can't grow food to feed the iPhone user.

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Notes:

1. Generally, Wikipedia, "Peak Minerals" https://en.wikipedia.org/wiki/Peak_minerals#Peak_minerals_an...