Survey Charge

Before you plant a mining quarry or a pump jack, you want to know what is under the ground, and the survey charge is how you find out. Throw it down, step back, and the blast leaves a small crater and shows which resources that spot holds. Both machines' own descriptions point you to it.

So the charge is only worth anything once you own one of them, and you cannot craft either: they come from loot. Picture the evening you pull a quarry out of a crate. You want sulfur, so you walk the flats near your base throwing charges until one spot reads well, and only then do you place it.

The cost is not trivial. Each one takes 30 gunpowder and 20 low grade fuel at a Level 2 bench, and the blueprint costs 120 scrap, as much as C4. Most groups never research it. If a quarry does fall into your hands, craft a handful rather than placing it blind.