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.
Old Psychopedia Description
"Carved straight from the infamous mother rock herself, these bits of Psitanium were shaped by the Indian tribes that originally lived and thrived at Whispering Rock. They were buried in the ground after creation for reasons few know about and even fewer care to, before the place was claimed as a boom town, a lake, and, later, a summer camp that isn’t really important. It was in this last stage of development that the arrowheads found new use, this time as a form of currency roughly equivalent to a dime a pop. While digging up money may seem pointless and rather silly, the release of gas from their lavender figures and the strategic use of your acclaimed digging-up-an-arrowhead-kinesis prove to make this venture easy, useful, and, perhaps, even fun.
For the deeper ones, as well, which are too far underground to belch noxious gas at you like a neon sign saying “ARROWHEAD HERE!” and are big enough to be worth quarters of moolah, there is a conveinent item in the camp store that may help you out a bit. And, hey, who doesn’t like free money? As for how they manage to not become extinct by children happily digging them up all the time and spending them, and how they always manage to regenerate whenever you leave and return to an area of the map, it is presumed that the counselors probably run out and bury them when the kids aren’t looking. However, this is still in debate, and staying up all night with a flashlight in order to check will only result in sleepiness and dream-crushing, like on that Christmas Eve when you were seven. You can lie all you want, you know it happened.
The Psychonauts would just like to add that the recent rumors of counselors receiving paychecks in the form of arrowheads are completely false. They only accept cash, loans, and blackmail."
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.