Brass Key

The Brass Key is the final key Heather Mason obtains in Silent Hill 3.

The item can be found inside a broken butterfly display case on the wall of Alessa Gillespie's room in the cult's chapel. The butterfly collection and key seems to have belonged to Alessa as well.

The brass key is used to open the locked door in the first corridor of the chapel. The following area leads to more rooms within the church, where Heather can find the tarot cards needed to progress.