Quick answer
Make Strontium by processing Celestine. Current reporting gives the working recipe as 2 Celestine into 1 Strontium in the Processor. Feedback Resonator currently needs 2x Strontium, so plan on at least 4 Celestine for that upgrade before you count spare stock.
Field notes for Strontium planning
This is a conversion bottleneck
Strontium is not the route; Celestine is. The Processor step only matters because it locks two raw pieces into one planned upgrade material.
Do the math before processing
Two Strontium means four Celestine. If you also want spare Celestine for later recipes, leave it raw until the next target is visible.
Keep it with resonator parts
Strontium is easy to misplace because it looks like a finished resource. Store it beside Feedback Resonator or module materials, not general minerals.
Strontium route plan
Treat Celestine as the real bottleneck
PC Gamer places Celestine around the Alien Ruins biome at lower depths. If you do not have a calm way to reach that area, the Strontium recipe will sit useless in your head.
Bring the Sonic Resonator
Large Celestine nodes need the Sonic Resonator. Do not swim all the way to the route with only hand tools and optimism. That is how a good route becomes a long sigh.
Use the Processor back at base
All Things How reports the recipe as 2 Celestine into 1 Strontium, processed at the base Processor. If the machine does not start, check power, input count, and whether you are using the Processor instead of another station.
Save it for actual upgrades
PC Gamer lists Strontium as part of the Feedback Resonator upgrade path, and All Things How says to process enough for at least two units. Treat 2x Strontium as reserved until that craft is done.
Mark the return route
Once you have one clean Celestine line, Strontium stops feeling rare. Drop a beacon or keep a landmark note so the second trip is a routine mining run.
Refining card
Mine
Celestine
Run the Alien Ruins route with Sonic Resonator ready.
Process
2 to 1
Use the Processor, not the Fabricator or random stations.
Spend
2x
Keep the first two Strontium for Feedback Resonator.
Strontium checklist
| Need | Why it matters |
|---|---|
| Celestine | The raw input for Strontium. Current guides point to the Alien Ruins depth route. |
| Sonic Resonator | Required for the larger Celestine nodes that make the trip worth doing. |
| Processor | The base station that converts Celestine into Strontium. |
| Tadpole depth planning | Celestine sits around the depth where hull limits and oxygen habits start to matter. |
| Upgrade priority | Feedback Resonator currently needs 2x Strontium, which means at least 4x Celestine before extra stock. |
Do not confuse the ore with the refined material
If a recipe asks for Strontium, raw Celestine is not enough. Mine the ore, go home, process it, then return to the Modification Station. It is a small extra step, but it is the step that causes most wasted trips.
FAQ
How do you make Strontium in Subnautica 2?
Current reporting says to put 2 Celestine into a Processor to get 1 Strontium.
Where do you get Celestine for Strontium?
Look around the Alien Ruins biome at lower depths. PC Gamer reports a strong route southeast of the Alien Ruins research base, near deeper rocks and Needler patrols.
Do you need Sonic Resonator?
Yes for the larger Celestine nodes. Bring it before committing to the route.
What is Strontium used for?
It is used in advanced upgrade planning. Current Feedback Resonator guides list 2x Strontium in that craft, alongside Enameled Glass and Conduit Crystal.
How much Celestine should I bring back for Feedback Resonator?
At minimum, bring 4x Celestine if you only need the 2x Strontium for Feedback Resonator. Bring extra if you still need Celestine for Modification Station or Tadpole upgrades.