Cooking Ingredient investigation spots can drop 1-3 units of the following Cooking Ingredients:
Forging Material investigation spots can drop 2-3 units of the following Forging Materials:
Non-respawning Mora Investigation spots (can be taken only once) can drop Mora ×500/1000/1500/2000.
The number of investigations a player can conduct in a day in the open world, is limited to 100. That is, after conducting 100 investigations, every investigation spot that the player gets close to, will not spawn. Investigation spots that already were in the player's vicinity when they reached the 100 limit, will not disappear (unless the player teleports away and then comes back). For example, if a player investigated 99 spots, and then entered an area with 30 investigation spots, the player will be able to take all 30, as long as they stay in that area.
Some Investigation spots can be found on the Teyvat Interactive Map.