Arrowheads are a unit of currency in Psychonauts. They are refined pieces of Psitanium fashioned in the form of arrowheads and buried beneath Whispering Rock Psychic Summer Camp by the area's previous Native American residents. They also appear in the mental world in the form of psychic arrowheads.
There are three different kinds of arrowheads: standard arrowheads, deep arrowheads, and psychic arrowheads. Standard arrowheads are worth one arrowhead and can be found all throughout Whispering Rock, marked by a purple geyser coming out of the ground. Deep arrowheads are buried deeper underground and are therefore only accessible after purchasing the Dowsing Rod from the Camp Store for 50 arrowheads. They are worth considerably more, ranging from 20 to around 200 arrowheads-worth per deposit. Psychic arrowheads are worth one arrowhead and are found by destroying objects and defeating enemies while in the mental world.
Arrowheads are primarily used to buy items at the Camp Store, the most important of the store's items being the Cobweb Duster which must be purchased to complete Milkman Conspiracy. However, as the Cobweb Duster costs 800 arrowheads, it is strongly recommended to purchase the Dowsing Rod first in order to find Deep Arrowheads, which are worth considerably more than the standard ones.