Dropped by the Alpha Wolf field monster, Apatite ore is on the same tier as Emerald ore in terms of strength and usability, but it's latent power is slightly different. It has the capability to access the Ice elemental, which is almost as effective against monsters that are similarly weak to the Water elemental, but also is strong against the seemingly unbalanced to the point of non-implementation Light elemental.
Much to be expected at this point, Apatite ore is only meant for weaponry, and it cannot be fused into armor to strengthen it. Armor can be decorated, but no different properties would be applied other than a cosmetic difference.
As to be expected as well, Apatite Ore-based weaponry has storage of energy for releasing the elemental, the more used at one time the longer it takes to recharge the capacity.
More uses for Apatite ore will be more apparent as the game progresses.