Caesium FAQ
What does Caesium add?
Hidden caesium ore (pegmatite), survey stations to find it, a short refining chain, and caesium parts for later machines: catalysts, photocathodes, scintillators, atomic clocks and atom traps. It also adds well treatment for oil and gas wells and, with Space Age, ion thrusters and an orbital survey array.
Factorio 2.1.20 or later in the 2.1 series is required. Space Age and all other mods are optional.
Why can't I see any caesium ore on the map?
Map generation never places pegmatites. They appear only when something surveys their chunk: a survey or magnetometer station, a seismic charge or shell, a survey satellite, or the orbital survey array. When a pegmatite is found, the patch is placed, charted and tagged on the map, and you get an alert and a chat line with a map link.
Where is the first patch?
Every planet with land has a starter patch 3–6 chunks from spawn. A survey station whose range covers it surveys it first, so a station built near spawn finds it within its first scan (10 seconds).
How often are pegmatites found?
About 1 chunk in 150 holds one, with none within 2 chunks of spawn. A survey station covers 169 chunks, so it finds about one besides the starter; a magnetometer station covers 625 chunks and finds about four. Patches are 30–70 tiles and hold about 800 ore per tile near spawn, rising with distance: a patch 40 chunks out is three times as rich per tile.
The Pegmatite frequency and Pegmatite richness map settings multiply both. Changing them affects only chunks that haven't been surveyed yet.
Does every player find the same patches?
Yes. Whether a chunk holds a pegmatite, and its position, shape and richness, come from the planet's map seed and the chunk coordinates. A survey only reveals what the seed already decided, so multiplayer and reloads give the same patches.
What are the basic recipes?
Standalone recipes before productivity, at crafting speed 1. Integrations may change the reagents.
| Recipe | Machine | Inputs | Outputs | Time |
|---|---|---|---|---|
| Pegmatite sorting | X-ray ore sorter (by hand: 10 s) | 20 pegmatite ore | 1 pollucite, 16 stone | 2 s |
| Pollucite leach | chemical plant | 5 pollucite, 20 sulfuric acid | 1 caesium alum | 5 s |
| Caesium carbonate | chemical plant | 1 caesium alum, 1 stone, 10 water | 1 caesium carbonate | 4 s |
| Caesium | chemical plant | 1 caesium carbonate, 1 coal (1 magnesium with Magnesium) | 1 caesium | 8 s |
| Caesium catalyst | assembler | 1 caesium carbonate, 1 iron plate | 20 caesium catalysts | 2 s |
| Photocathode | assembler | 1 caesium, 1 iron plate | 5 photocathodes | 5 s |
| Scintillator crystal | chemical plant | 1 caesium, 1 stone | 1 scintillator crystal | 10 s |
| Atomic clock | assembler | 1 caesium, 2 advanced circuits, 5 steel plate | 1 atomic clock | 15 s |
| Atom trap | assembler | 1 caesium, 1 processing unit, 2 steel plate | 10 atom traps | 10 s |
| Formate brine | chemical plant | 1 caesium carbonate, 20 water, 10 petroleum gas | 100 formate brine | 2 s |
How does the Phosphorus retort route work?
At Caesium metal research, a chemical plant combines 2 caesium carbonate + 1 magnesium → 2 reduction mixtures in 4 seconds. Without Magnesium, it uses 1 coal instead. Feed each mixture into a phosphorus retort to make 1 caesium metal in 6 seconds. This saves 50% of the magnesium or coal compared with direct chemical-plant production, in exchange for the extra machine and handling. Carbonate and any packaging materials stay at their full cost per metal. Preparation cannot use productivity. Existing mixture stock and retort setups keep working; setups from before 0.1.3 need their carbonate feed replaced with mixture.
Why do I need an X-ray ore sorter?
Pollucite looks almost like quartz, so real mines sort pegmatite by X-ray. Pegmatite sorting runs only in the X-ray ore sorter (3×3, Caesium processing research) at 1 sort every 2 seconds. Its construction includes two fast inserters for material handling. If your pack makes fast inserters require antimony, the sorter inherits that cost. Hand sorting is optional and five times slower; it is not required to build the sorter. With Neodymium, its magnetic separator also sorts pegmatite and gets a quarter more pollucite.
How much caesium do I need?
One electric drill on a pegmatite gives about 18 caesium an hour. A mid-game base with a catalysed acid plant, a treated oil field and a few stations uses about 25 an hour; a late game uses 80–140 an hour from two or three patches.
What needs caesium?
Several existing machine recipes require Caesium parts and the matching research:
- laser turrets and personal laser defense: 1 photocathode each;
- centrifuges: 1 scintillator; nuclear reactors: 2 scintillators;
- beacons: 1 atomic clock; satellites: 10 atomic clocks (Space Exploration: 5);
- night-vision equipment, where its research comes after blue science: 1 photocathode;
- Space Age: 1 atomic clock per platform starter pack, 1 atom trap per quantum processor, 1 atom trap per 10 cryogenic science packs;
- Krastorio 2: superior night vision, the GPS satellite;
- Space Exploration: gamma-ray detectors, observation frames, quantum processors;
- AAI Signal Transmission: signal senders and receivers.
The caesium catalyst for sulfuric acid is optional.
How does well treatment work?
Place a well treatment station within 8 tiles of oil or gas wells and feed it formate brine. Every 10 seconds a treatment uses 10 brine and adds 2,000 to the most depleted well in range, while the pumpjacks keep running. The station pauses while every well in range is back at full yield. Holding one well at full yield costs about 1.8 caesium an hour.
The cap is the well's initial amount, so it only works on infinite wells (vanilla, Space Age, BZ, Space Exploration). Formate keeps wells producing but adds no reserves: with Krastorio 2's finite oil, well treatment isn't available.
How do ion thrusters work?
An ioniser (2 MW) turns 1 caesium into 1,000 caesium plasma in 1,000 seconds, which feeds one ion thruster at full power. An ion thruster gives about a third of a thruster's thrust on a tenth of the fluid, and needs no thruster fuel or oxidizer: about 3.6 caesium an hour and 2 MW per thruster. Platforms fly slower on them, so they suit supply shuttles.
What happens when I add Caesium to an existing save?
Everything starts unsurveyed and each planet's starter patch is still there. If you already researched something that now needs caesium (for example the rocket silo), the Caesium research it depends on is granted with its prerequisites, so no recipe gets locked.
Does it work with other mods?
Space Age, BZ, Krastorio 2, Space Exploration, Timeken, Planetfall, AAI Signal Transmission and the sibling mods (Cadmium, Tellurium, Magnesium, Phosphorus, Gallium, Neodymium) are supported.
With BZ and Timeken, the chain uses the real materials where they exist: silica and alumina come out of sorting and the carbonate step, quicklime replaces stone, ampoules are sealed under argon, atom traps get indium seals, and the atomic clock gets titanium, a graphite getter and a nickel shield. Space Exploration's core miners don't find pegmatites. Mods that hide or move all ores, such as Underground Resources, are not needed and not handled specially.
How do I build the first survey station?
Research Radar, Steel processing and Geological survey. The station costs 1 radar, 5 steel plates and 5 electronic circuits and takes 10 seconds to craft. Geological survey uses red and green science in vanilla; in overhaul packs it also follows the research and science packs needed for its ingredients. Survey and magnetometer stations occupy 3×3 tiles, the same as a radar. Existing stations keep their positions and continue working after updating.
What uses Caesium in vanilla?
Laser turrets and personal laser defense each require 1 photocathode. Centrifuges require 1 scintillator, nuclear reactors 2, and beacons 1 atomic clock. Satellites still need 10 atomic clocks. These change the existing recipes, with matching research prerequisites. Catalysed sulfuric acid and well treatment remain optional uses.
Do survey stations share progress?
The map remembers which chunks have been surveyed. Each station counts surveyed chunks only within its own range, so overlapping stations share that progress and avoid scanning the same chunks twice. Stations in separate areas have separate progress. “Area surveyed” is that shared local coverage; “Own finds” counts discoveries made by this station. Moving or rebuilding a station preserves the map's survey history but starts that station's own discovery counter over.
Once all 169 chunks are surveyed (625 for a magnetometer), the station stops scanning and displays “Area fully surveyed”. Move it or build farther out to survey new ground.
Will I be notified when a deposit is found?
Yes. Each newly revealed deposit gives connected players on the discovering force a map alert and, by default, a highlighted chat message with an ore icon, the ore amount, a clickable GPS link and a notification sound. Discovery chat can be disabled in the per-player mod settings; the sound follows your chat sound preference. Overlapping scans do not announce the same deposit again.