Mars

Mars has a very thin carbon dioxide (CO₂) atmosphere about 0.6% of the pressure of Earth.
Pulling a rough vacuum with a simple passive water-jet-vacuum-pump
one ends up at roughly the same pressures but with water vapor gas instead of CO₂ (at room temperature).

Surface pressure:
– from the deepest: ~11.5millibars, Hellas Planitia, 7 kilometers (4.3 miles) deep, a massive impact basin in the southern hemisphere of Mars
– over average 6.1millibars
– to the highest: ~2millibars, Olympus Mons, 22 kilometers (13.6 miles), biggest volcano in the solar system) point.

Surface temperature:
– 20°C (68°F) at the equator during the day
– -60°C (-76°F) typical average surface temperature
– -125°C (-193°F) at the poles during winter nights

The thin atmosphere makes for more micro(meso?)meteorite impacts and
for more solar and cosmic radiation hitting the surface.
The lack of a Magnetic field like on Earth contributes to the latter.
Eventual settlers either need to go underground or under thick domes which may be transparent.
beside the typical gem-gum base materials even water ice works.

Resources in the context of gemstone based APM

Carbon dioxide for carbon

Just like on Venus the CO2 in Mars' atmosphere can serve as
a good simple standard shape resource molecule for carbon (and oxygen) for future gem-gum factories on Mars.

Water for hydrogen

By now (2024) we know that there are quite a lot of water ice reserves on Mars.
While there is a lot of dry ice (frozen = carbon dioxide) at the polar caps there is water ice too.
Beyond there polar regions there is still a lot subsurface ice.
Partial pressure of water vapor should be very low though due to low average temperatures
and warm places being rather dry. So extracting water via the air as a byproduct will take patience.

Other elements

Solubles:
Martian soil supposedly contains high concentrations of perchlorates that can be washed out with water.
beside a source of chlorine (Cl) also a potential source of chlorine and conterions. Mostly the abundant ones Na, K, Mg, Ca.
Other salts of less abundant halogens and (rarth)alkalis may be present too in the dunes. Just guessing.

Locked:
Silicates (Si) and aluminates (Al) are obviously present being most abundant elements in terrestrial planets.
Iron (Fe) even shows by Mars's color. What about the gem-gum tech relevant element titanium (Ti)?

(wiki-TODO: Cover nitrogen, sulfur, phosphorus)

Ceres in comparison for space colonization

An interesting alternative to colonize that is rarely considered is planet Ceres.
Some potential advantages include:

• direct access to the main asteroid belt in close solar orbits
• lower gravity making leaving the place much less costly in terms of delta v
• lower gravity and allowing for 1g vertical rotating cylinder gravity (rather than impractical bowl shape on Mars)
• lower gravity (and volatile rich ground) allowing for deeper easier mining for resources and habitation space
• more water ice and volatiles, likely including ammonia as nitrogen source
• known hydrothermal vents that likely concentrated minerals
• not much less space radiation and micrometeorite as Mars' atmosphere is so thin
• Ground based mass decelerator? Seems questionable though

Slight downsides:

• a bit farther out than Mars to travel to (but this gives access to the entire asteroid belt too)
• a bit farther out than Mars and thus less solar flux for solar power (it's not an extreme drop though)
• ground is likely carbon rich material but that's still not quite as convenient as sucking CO2 directly from the atmosphere
• No aerobraking as on Mars, especially for non Hohmann shorter travel time trajectories that dominate compared to delta v from Mars' gravity well

External links

Very good panoramic picture taken by the Curiosity rover showing interesting terrace structures going up mount sharp.
https://photojournal.jpl.nasa.gov/catalog/PIA24180
This panorama, made up of 122 individual images stitched together,
was taken by NASA's Curiosity Mars rover on November 18, 2020,
the 2,946th Martian day, or sol, of the mission.