diff --git a/tilemap/docs/dev.md b/tilemap/docs/dev.md
index 6f7626e..245f4de 100644
--- a/tilemap/docs/dev.md
+++ b/tilemap/docs/dev.md
@@ -59,6 +59,7 @@ Terrain generation uses a multi-pass pipeline for modularity and control:
 6. **Deep Water Pass**: Places deep water areas
 7. **Oil Pass**: Generates sparse oil deposits as surface features
 8. **Mineral Cluster Pass**: Generates mineral clusters (Hematite, Titanomagnetite, Gibbsite) on mountain edges using cellular automata
+9. **Coal Pass**: Generates coal deposits using a cellular automata approach
 
 Each pass operates independently with its own RNG state, ensuring deterministic results.