The September playtest announcement places cobalt and graphite in other sectors of your starting solar system after the Slipstream Drive stage of research. Look beyond the opening area and plan a trip to a sector where your map identifies a useful deposit.
Reach the wider system first
The developer described travel to other sectors as a step beyond the original demo's Slipstream research endpoint. Make sure your current build gives you access to that stretch of progression before spending time searching the opening belt.
Use sector information to choose a target
Look for fields that show the material you need. A player on an experimental build reported finding cobalt by zooming out and inspecting asteroid fields on the map. That experience helps with the search process, though deposit positions vary by save.
Bring the resources back for research
The playtest announcement connects these resources with Electromagnetic and Quantum Science. Gather a test shipment first and check the requirements in your own research menu before committing to a permanent outpost.
See Main Sequence's official Steam update feed for the official game information.
FAQ
Are cobalt and graphite in the starting belt?
The documented playtest path sends players to other sectors of the starting solar system.
Do I need interstellar travel?
The playtest announcement places these resources within the same solar system, before the Interstellar Warp Drive step.
Does the October demo follow the exact same path?
The October demo update added Electromagnetic Science. The documented location and progression description here is from the September playtest.