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 2.1.23 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 pegmatites has a starter patch 3–6 chunks from spawn (Aquilo, space platforms and surfaces that aren't a planet have none). 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.

How do survey satellites work?

Launch a survey satellite in a rocket. It surveys one new chunk per second for ten minutes of game time, up to 600 chunks. Pausing the game pauses the mission. It automatically works outward from the planet's origin, regardless of where you built the silo; there is no target to select.

All satellites on a planet share survey progress, including ground and seismic surveys. Already surveyed chunks don't spend a scan. Two active satellites survey two new chunks per second, and a replacement continues where earlier missions stopped. Launch one every ten minutes to sustain one satellite's coverage. A fully surveyed finite map has no new chunks left to scan.

Launch and expiry messages report mission status. Use /caesium-survey to see your force's active satellites, remaining seconds and scan counts on your current surface. Found deposits stay on the map after expiry; satellites never refill mined-out deposits. At default Nauvis frequency, 600 fresh chunks contain about four random deposit candidates on average, before terrain restrictions; a launch does not guarantee four usable patches.

Existing saves keep all previous surveys and discoveries. New launches skip those chunks and expand coverage. With Space Age, orbital survey arrays retain their existing continuous operation instead of timed satellites.

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?

These are the Fluffy-only starter recipes. External material packs add the production stages described in this FAQ.

Standalone recipes before productivity, at crafting speed 1. Integrations may change the reagents.

How does the Phosphorus retort route work?

With Space Age, coal-fed mixture preparation can use one carbon instead, with the same costs and output.

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.

Can the X-ray sorter process surplus stone?

With Neodymium, first wash stone into heavy mineral sand in a mineral spiral. Mixed-metal sand sorting takes 4 sand and gives 1 copper ore in 4 seconds, plus independent 2% tin and lead chances when those ores are installed. The recipe requires both Caesium processing and Neodymium processing and uses no operating magnets. It rejects productivity and quality.

The standard washing bill is 40 stone and 200 water for four sand before productivity. This gives surplus stone a small recovery value while retaining the water and processing logistics. You can still send the sand to monazite or iron-rich sorting instead.

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, but takes one operating magnet per craft and returns it with 98% probability. Loop the return and supply replacements: on average one magnet per 50 crafts. The X-ray sorter needs only ore and electricity, making it useful at outposts without magnet deliveries. Existing magnetic sorters keep their recipe and buffered materials after updating, but need magnets supplied to resume.

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. A treatment takes 10 seconds, uses 10 brine and restores 2,000 to the most depleted well that can absorb the full dose, while the pumpjacks keep running. The station pauses until a well has at least 2,000 depletion, so it doesn't waste doses topping off nearly full wells. Maintaining one well near its initial yield costs about 1.8 caesium carbonate an hour with a normal-speed pumpjack, after restoring its earlier depletion. Faster pumping needs proportionally more treatment.

If another station fills the well first, a completed dose waits until it can be used in full. A craft already in progress stays buffered while paused. Both survive saving and loading; no extra brine is needed to restart them.

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.

Ionisers and ionisation work only on platforms. Ion thrusters can replace normal thrusters in place.

Where do I get caesium in Space Age?

Survey pegmatites on Nauvis, Vulcanus (1 in 120 chunks, 1.5 times richer), Gleba (1 in 150) and Fulgora (1 in 240). Fulgora can reduce one carbonate with one solid fuel from scrap in 8 seconds. Gleba can use one carbon instead of coal, or bioleach 5 pollucite with 2 sulfur, 1 bioflux and 20 water into 1 alum in a biochamber in 10 seconds. Bioleaching has no productivity bonus and follows both Caesium processing and Bioflux research.

Aquilo recovers carbonate from lithium brine after Caesium processing and Lithium processing, returning 90% of the brine. Local solid fuel can finish the metal step. Atom traps still need imported processing units and steel. Platforms import caesium; orbital arrays survey the planet below.

Electromagnetic plants make clocks, photocathodes and atom traps, including Gallium photocathodes. Cryogenic plants run the chemistry steps; the original machines still work. Infinite refining productivity uses red, green, blue, space and cryogenic packs at 60 seconds per unit, costing 1000 × 1.5^level for +10% metal per level, including Phosphorus distillation. Factoriopedia and a new tip explain the sources.

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, Antimony, Molybdenum) 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.

Which planet mods does it support?

• Hyarion: Twice as many pegmatite deposits, richer than usual.
• Muluna: No pegmatites; bring caesium with you.
• Secretas: No pegmatites; bring caesium with you.
• Corrundum: Use a caesium catalyst to make extra sulfuric acid from the planet's sulfur dioxide.

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.

How much caesium does magnesia recovery make?

The optional Magnesium integration has a 1% chance of one caesium carbonate per craft, averaging one per 100 crafts (200 magnesia with the base recipe). This is twenty times the previous 0.05% chance. Inputs, magnesia output and crafting time are unchanged. Existing recovery plants adopt the new chance on update; ordinary magnesia keeps its original outputs.

What do the material-pack integrations add?

Refining adds purification slurry and filtration. Sealed vapour cells feed instruments, clock chambers collect their precision parts, and scintillators pass through blank growth and finishing. A reachable Phosphorus retort makes preparation and distillation the ordinary reduction route. Existing glass, seals, gases and suitable foundries or crystal pullers supply these stages.

Will this change my Fluffy-only factory?

Fluffy-only games keep their existing recipes, machines and progression, with or without Space Age. The extra requirements activate only with the relevant external material providers. They do not add machinery requirements to a normal Fluffy-only game.

How should I update a factory that uses material packs?

Back up your save and update the Fluffy material mods you already use together. You do not need to install additional siblings. Existing external production lines may need new ingredient feeds, intermediate transfers or a different crafting machine. Saved materials and recipe references are preserved; check around machines for returned stock after upgrading.

For this coordinated release, the companion versions are: Molybdenum 0.4.7, Neodymium 0.3.5, Magnesium 0.6.2, Phosphorus 0.3.2, Gallium 0.3.3, Antimony 0.4.5, Cadmium 0.5.1, Tellurium 0.4.0 and Caesium 0.3.0. These mods remain optional. If Antimony or Molybdenum is installed with Caesium 0.3.0, it needs at least 0.4.5 or 0.4.7, respectively.

Provider conflicts still apply. BZ + Trikop is supported; Manganese on its own has an upstream steel-furnace limitation that can block progression. Space Exploration and Space Age are separate configurations.