There are 68 forging materials to locate in Tales of Arise. These can be found as enemy drops and in some chests, and are used to forge new weapons for the party. This page details the location and use for the Tempest Stone.
Tempest Stones can be found in Aqfotle Hills.
||Menancia - Mount Dhiara, Mahag Saar - Aqfotle Hills
Weapons Forged with Material
||Nature’s Beauty: 2nd Ed.