The old Judges’ Guild Wilderlands of High Fantasy also had prospecting rules.
Honestly, either the Dungeoneer’s Survival Guide or Aryx’s rules will be more useful. Dragon 157 refers back to the DSG for most of the basic rules, and is an accessory to those rules rather than a standalone set.
The Complete Book of Dwarves itself might be an option too, if it’s easier to find than the DSG. (I cannibalized the stuff that I thought was useful, but you might have a different opinion!)
Just doing a shallow eBay dive, it looks like either DSG or CBoD can be gotten for $10-15 including shipping.
While I’m not as fond of it as I am of the DSG, the Wilderness Survival Guide does have some potentially useful things as well. Pages 53-60 cover foraging, hunting, fishing, and finding water, based on climate zone (arctic, subarctic, temperate, subtropical, and tropical) and terrain (desert, hills, mountains, plains, forest, swamp, and seacoast).
Pages 69-70 cover the odds of finding medicinal plants in the wild.
Those two sections are the most relevant to a Roanoke-style campaign. It also covers finding enough wood for a fire and finding natural shelter in the wilderness, but not rules for finding exploitable resources.
Our GM has decided he’ll definitely use ACKS as the core framework, with the occasional supplement to determine available resources.
On a wholly unrelated note, are there any RPGs that cover the sort of ACKS endgame, but in a space setting? I know that Rogue Trader is supposed to, but the more I interact with it, the more it comes across as incredibly clunky.
in a way more abstract style stars whitout number covers conflicts for planetary and interplanetary factions.
I’m thinking about writing one. Is that the same thing? 
(Some time ago, I had the idea that a planet = a six mile hex and a system = a 24 mile hex, and realized that from this I could port the basic concepts of ACKS into a sci-fi setting with relative ease. I haven’t really started it yet, but the kernel is there.)
You could also look to the excellent (and free!) Stars Without Number from Sine Nomine publishing for inspiration.
SWN’s Suns of Gold supplement also has rules for colonizing new planets; combined with the faction rules in their core book, it gets kinda close to ACKS’ domain capabilities, though at a much lower degree of granularity / higher level of abstraction.
If he’s willing to share, I know at least some of us would be very interested in seeing what he comes up with for resources. That’s been one of my hang-ups for doing a completely random sandbox.
One day I will write an ACKS-style space opera game to allow a 4X space strategy experience.
When that day comes you will claim yet more of my money
I eagerly await your spreadsheets of speculative future economics.
And tables! Lots and lots of tables…
If you ever need an economics consultant, just let me know. Also, I would buy this in a heartbeat.
If you can pull off a sci-fi game that is as economically consistent as ACKS, I will be very impressed.