On the contrary, Zubrin presents a detailed account of the chemical analysis of three separate types of lunar soil...............
Basalt{Apollo 11},
Breccia {Apollo 14}
and Regolith {Apollo 17}.........
in Table 5.1, page 80 of ENTERING SPACE so your assessment may be mistaken.
.........so his opinion on the amounts of resources and effort to mine them are uninformed........
This data is public knowledge and has been published by Haskin & Warren, "Lunar Chemistry", Chapter 8 of LUNAR SOURCEBOOK (Cambridge University Press). If he is 'uninformed' then so is the rest of the scientific community because these are the only samples available unless you are aware of anyone else landing on the moon and returning soil and rock samples for analysis.
I'm not going to try and type several pages of analyses, however.............."while the Moon's rocks and soils possess ample supplies of oxygen and several important metals, they are entirely lacking in such vital substances as organics, hydrates, nitrates, sulfates, phosphates and salts.......key primary biogenic elements of hydrogen, carbon and nitrogen are present on the moon but in general only in extremely rare quantities..........leading secondary biogenic elements, sulfur and phosphorous are also on the rare side" (My Conclusion: We will have to supply our own manure if we want a self sufficient colony; lunar soil will not support growth of plants........under domes, of course)...........
"..........leading secondary industrial elements, potassium, manganese, and chromium are reasonably common but nickel is scarce and cobalt even scarcer while copper, zinc, lead fluorine and chlorine are extremely hard to come by........."
He goes on to discuss the myriad of other problems with bases on the moon.
Hardly lacking in 'detailed knowledge' or written from an 'uninformed' standpoint. No?
No, actually I stand corrected. It's not "uninformed" -- it's irrelevant.
It does not address the presence of water ice in the dark areas, first discovered by Clementine in 1994 and then confirmed by Lunar Prospector in 1998. It's the water on the Moon that's valuable, both for human life support, but even more importantly, to make propellant for rocket engines.
BTW, "basalt", “breccia”, and "regolith" are descriptors of general rock types, present at all landing sites and widely distributed across the Moon. They are very common, but that does not make them "valueless" -- it depends on what you're trying to do. We wouldn't go to the Moon to mine common metals; but we would use common materials to build things on the Moon -- or in near-Earth space.
The definition of a "resource" is economic, not geological. It's anything you can make a profit on. You can make money on mining lunar water because it's cheaper to get rocket fuel from space than it is to haul it up from the surface.
Zubrin is blinders-on for his "Mars Direct" architecture, so he wouldn't think about using lunar resources to develop the Moon or build structures in near-Earth space. But those are real possibilities. And the Moon can provide the resources for it, regardless of what you find written in Zubrin's book.