A small number of posts in the Investor quagmire regarding the eventual forging on Mars of semiconductor chips prompted my thinking of raw materials necessary to an extraterrestrial colony. Many of these have been discussed or at least alluded to either in this thread, elsewhere within TMC, in popular media and amongst specialized Martian publications.
The latter I have not good access to, and perhaps the following topic has been addressed there. Happy to learn if someone knows any other discussion re same.
Easy ones to consider, if not to solve for: water, oxygen, energy, iron, silicon, steelmaking alloys like Ni, Cr, Co and others. Battery raw materials like Li, Ni (again). Soilmaking enrichers like Ca, K, P, N. Saline anodes like Cl. Monster anodes like F.
My concern is with another element, one ubiquitous not only in humans' daily lives but omnipresent also in all phases of the transportation sector - aluminum. Now, Al (that's not AI but Al. Do you see the difference? No, neither do I. First abbreviation is for Artificial Intelligence and the second is for element #13, Aluminum/Aluminium). Al is indeed well-thought to be approximately as common in Martian crustal material as it is on Earth - about 5th in abundance after Si, O, Fe, Mg. The BUT is, however, extraordinarily large and troublesome.
Exactly 100% of all primary aluminum mined on the earth comes exclusively from deposits formed in just one way: the extreme action of rainfall over not millions, but many tens or hundreds of millions of years. Once aeons of rainwater have leached out everything else: all the other rockforming elements like magnesium, sodium, and even silicon (did you think quartz - SiO2 - is hard and weatherproof? Not by geologic time standards it isn't), and even the removal of that second-most resistant material - iron oxide - that which is left over is aluminum oxide (bauxite & ilk). There is NO other source* of aluminum.
And, unless the former Martian water processes now quiescent for X*10^9 years had been strong enough and prolonged enough to have acted similarly, then aluminum will not be available on Mars.
Why not, you ask, if the energy problem can be solved and the element is indeed present in Martian crust? Because rockforming mineral that contain aluminum - feldspars and so forth - divulge their elemental metal even more reluctantly than that so-called hardest of all metallic nuts to crack - aluminum oxide (bauxite). Aluminum so derived is called 'canned electricity' for good reason. Attempting to concentrate Al-poor sources into pure feldspars, and then releasing that metallic Al, would be many times more energy consumptive.
A way to put historical perspective on this: prior to the development of the Hall-Herout method of electrosmelting of bauxite, Aluminum metal was so rare that it was more precious than gold, and Queen Victoria was gifted an incalculably valuable aluminum service as a gift (now retailing at Wal-Mart for $27.99........).
So. What to do? Three answers from me.
1. Refer back to the propreantepenultimate paragraph's *asterisk. For a short number of decades, there was ONE other source of aluminum; one not a function of weathering but rather, from 'pure' magmatic action. A rare mineral in pegmatites - that final exhalation from a cooling magmatic chamber, and one in which all the hard-to-incorporate into "regular" rock-forming minerals (boron, beryllium, lithium, uranides and so forth) - is a sodium-aluminum fluoride called cryolite. It has been found in minute quantities in a small number of pegmatites in Colorado, Russia and China....and in exactly one single location in coastal southern Greenland where it was a large enough deposit to be mined from the 1860s until exhaustion after WWII.
There is no reason at present to believe that magmatic intrusions like pegmatites might not once have occurred on Mars. Those in which cryolite has been found seem to share gneisses as their matrix - some gneiss is highly feldspathic and possibly the pneumatolytic fluids associated with the proto-pegmatite leached Al, to be grabbed by that most vellicate of elements, F, to create cryolite. A concerted search for pegmatites peripheral to, for example, Elysium Mons or Hecates Tholus rather than that most familiar gargantuan Olympus Mons, as the latter is too similar to Earth's shield volcanoes to be a likely former of pegmatites. But areology remains hardly even in its infancy and it is risible to consider a keyboardist's ramblings as an authoritative guide to mineralogic exploration.
2. Consider Earth as the source for Al and calculate the costs of importing either ingots or pre-created alloys for.....¿perpetuity?
3. Embrace the lowered gravity of Mars and substitute iron and steel for items that on Earth would be made from aluminum.
Cost-Benefit analyses await....