Quick answer
If you can already resurrect zombies but 
Zombie Mining, 
Zombie Lumberjack and the other gathering technologies are completely missing from the technology tree, that is normal. They stay hidden until you open both ends of the Old Mine: blast the collapsed Quarry cave and clear the passage between the Factory and the mine.
Opening only one entrance is not enough. Once Quarry → Old Mine → Factory is connected, the hidden gathering branch appears. You still have to buy each technology, build the appropriate stand, assign a zombie with the correct tool and add Porter Stations where you want automatic transport.
Why are the zombie gathering technologies missing?
This is one of Graveyard Keeper 2's least obvious progression gates.
You can already have:
several resurrected zombies;
automated workstations;
Iron production;
significant story progress;
and naturally start looking for the technology that finally stops you from chopping trees and mining resources manually.
But it is not greyed out.
It is not shown behind a question mark.
It is simply hidden.
The game reveals the resource-automation cluster only after the Old Mine is physically connected from both sides.
What is the Old Mine?
The Old Mine runs below the forest between the Quarry and the underground Factory.
It has two entrances:
- 1
the collapsed cave at the Quarry;
- 2
the passage from the Factory beneath your home.
You can enter the mine after opening either side.
But zombie gathering requires both sides to be open.
That creates the common situation:
“I am literally standing inside the mine. Why is Zombie Mining still missing?”
Because visiting the mine and unlocking its automation are separate progression checks.
Step 1: open the Quarry cave
At the back of the Quarry is a blocked cave.
Continue the forest story until you meet Hans and Sven and reach the point where the blockage can be dealt with.
The cave is opened with 
Dynamite and sufficient Building Mastery.
Once the rubble is gone, you can enter the Old Mine from the Quarry side.
Do not worry if the zombie technologies still do not appear.
The Factory side is still required.
Step 2: open the Factory
The Factory is the large underground industrial area connected to the basement beneath your house.
Factory entrances require more advanced construction materials, especially 
Reinforced Beams.
This is where several progression systems converge:
Iron;
advanced woodworking;
Town development;
the underground Factory;
zombie automation.
If the wall is visible but its material requirements are currently impossible, you are probably not softlocked. You simply have not reached the right production tier.
Step 3: clear the Factory-to-Mine blockage
At the south end of the Factory hall is the passage into the Old Mine.
The blockage requires:
Clear it.
If the Quarry cave has also been blasted, the route is now fully connected:
Quarry
↓
Old Mine
↓
Factory
↓
your production network
This is the trigger that reveals the hidden zombie resource technologies.
What becomes available?
The automation branch covers the major raw-resource systems:
These are not one universal “automate resources” purchase.
Each needs its own technology and physical infrastructure.
Zombie Miner: renewable Iron and Coal
The Zombie Miner is built inside the Old Mine.
Each work cycle produces:
The worker repeats the cycle automatically.
This finally solves the early Iron problem where surface deposits are finite and you keep searching the world for another orange rock.
If you only need your first Iron before reaching this system, use How to Get Iron Early.
Which tool should the Zombie Miner use?
A Pickaxe.
Tool quality matters a lot.
Do not put a fresh zombie there with a 
Rusty Pickaxe, watch it crawl through one cycle and conclude that zombie mining is useless.
A 
Bronze Pickaxe is much faster, and an 
Iron Pickaxe improves the job dramatically.
Like normal zombie production, the worker uses its own capabilities. Your Keeper's Mastery does not transfer to it.
See How Zombies Work.
What does the mine Porter Station do?
The miner puts its output into the Old Mine's local storage.
A Porter Station moves 
Iron Ore and 
Coal onward to the Factory.
Without a porter:
mining still works;
resources accumulate locally;
you collect them manually.
With a porter, the outpost becomes part of your automated production network.
Zombie Lumberjack: automatic wood
Wood automation lives at the Sawmill.
After purchasing Zombie Lumberjack, build the lumberjack infrastructure and assign a zombie with an axe.
Each cycle brings in:
The local Porter Station can then send wood to the Factory.
This becomes extremely valuable once Town restoration and Factory production start consuming large quantities of wood.
Zombie Stone and Marble Quarry
At the Quarry you can build dedicated zombie quarry structures.
Stone
Zombie Stone Quarry provides renewable 
Stone.
The assigned worker needs enough Building Mastery. A fresh zombie usually needs a suitable Pickaxe rather than its default weak setup.
Marble
Marble automation is a later, more demanding version of the same idea.
If the zombie stands at the job and does absolutely nothing, check its Mastery and tool before blaming logistics.
Clay and Sand automation
Zombie Digging unlocks gathering infrastructure for:
Sand feeds:
the Sluice Box;
later crafting chains.
Clay feeds:
The manual pits are renewable, but automatic digging removes a lot of repetitive travel and shovel work.
Why is my gathering zombie idle?
Check these in order:
- 1
did you buy the revealed technology?
- 2
is the correct stand built?
- 3
- 4
does it have the correct tool?
- 5
does that zombie have enough Mastery?
- 6
is local storage available where needed?
- 7
remember that a Porter handles transport, not the basic gathering action.
The most common issue is the worker's own Mastery.
Do I have to unlock the Factory first?
For the full hidden gathering branch, yes: you need the connection from the mine into the Factory as well as the Quarry entrance.
You can physically visit the Old Mine earlier from one side.
That is exactly why the system is confusing. Entering the location does not equal completing the automation trigger.
What should you automate first?
A strong general order is:
1. Iron and Coal
Metal is needed throughout progression, while Coal feeds later smelting.
2. Wood
Town rebuilding and Factory production consume a huge amount of wood.
3. Stone
Useful for construction and kit production.
4. Sand and Clay
The manual sources are renewable, so they are less urgent, but automation is still a major convenience.
5. Marble
Important later and more demanding on the worker.
FAQ
I opened the Old Mine but Zombie Mining is still missing. Why?
You probably opened only one end. The Quarry cave and Factory passage both need to be open.
Does the Miner need a Supplier zombie?
Not to mine. It stores output locally. A Porter moves those resources onward.
Why is my Stone zombie idle?
Check its Building Mastery and Pickaxe.
Can zombies gather Sand and Clay?
Yes. Zombie Digging unlocks the relevant stations and Porter support.
