A few Elemental suggestions.

[RTLittletree]

I was playing my most recent run of ONI and my brother suggested it would be nice to add sodium to the game, which would allow for Chlorine/Sodium generators, which would produce common table salt, and a lot of energy. The sodium itself would require care, as it would react by producing LOTS of heat if exposed to water (especially unfortunate messes) or chlorine gas. Perhaps having the mineral only appear in isolated pockets a good ways from spawn would help reduce the danger to the crews of random sodium fires. On the other hand the salt from thr sodium cloride generator would help reduce food based stress by slightly impoving the taste of food.

A source of solid carbon, possibly from processing coal, or carbon dioxide into raw carbon would be helpful, raw carbon would be a filtration medium and you could have it usable as a material for advanced construction projects by having a converter that makes carbon nanotubes, which can be used to make all kinds of interesting things eventually. I think both of these would do well in the last row of research. Good for extending the longevity of of late game colonies with renewable supplies.

[TrustyFish]

This reminds me of a big element that is missing... FIRE. Basically any spontaneous chemical reaction at all. (presumably there's plenty of chemistry going on inside machines) Theres lots of oxygen, and lots of combustible materials around. I can see why its missing at the moment, it could be both hard to simulate and be too dangerous to make for a fun play environment for a lot of players, but its something to keep in mind.

[ImpalerWrG]

See my posting here 

For a similar thought, I started more with Salt on the map and came to Sodium as a byproduct.

With regard to carbon, coal should just be considered pure carbon already, perhaps call it graphite instead of coal (geologically 'coal' as in fossil plant derived fossil fuel makes no sense on an asteroid, but primordial graphite that condensed from the solar nebula is fine.

[Phara0h]

I think the idea of turning co2 into coal would be great. I was looking for some kind of post related to the idea of converting co2 into something useful but other then feeding the slicks it's really annoying. I use mostly natural gas to power my colony in exchange I get tons of unused co2. It's horrible. 

There's got to be a way to use it up so it doesn't take up my air pressure. That or if we could puncture a hole in the asteroid to vent any over pressure gaseous element out into space that would be nice.

[Kasuha]

25 minutes ago, Phara0h said:

I think the idea of turning co2 into coal would be great. I was looking for some kind of post related to the idea of converting co2 into something useful but other then feeding the slicks it's really annoying. I use mostly natural gas to power my colony in exchange I get tons of unused co2. It's horrible. 

You can process the CO2 into polluted water with CO2 scrubbers if you have enough supply of clean water, or you can feed it to slicksters. Slicksters produce crude oil so technically it's processing CO2 into petroleum or plastic. Not mentioning you can get slickster eggs.

[Kazumiya]

If you turn CO2 into coal, hatchers become useless, since it's already easy enough to produce CO2 just by breathing....

[Phara0h]

17 hours ago, Kasuha said:

You can process the CO2 into polluted water with CO2 scrubbers if you have enough supply of clean water, or you can feed it to slicksters. Slicksters produce crude oil so technically it's processing CO2 into petroleum or plastic. Not mentioning you can get slickster eggs.

Ohhh.... Oh my. Thank you. This changes everything.

Edit: It was there the whole time. SMH, again, ty

[Flydo]

Need Radium, i see recently mercury is added to the material construction, they probably are cool thing to do with a liquid toxic metal how made thing with it if you need to cool it down before (and probably the machine must stay under -40°C to don't melt