(I apologize for multiple posts in a row.)
I just noticed, the spell Elemental Weapon causes a weapon to inflict acid, cold, fire, lightning, or thunder damage.
While most of us take it for granted, these damage types are ‘Elemental’ magic.
Air = lightning and thunder damage types
Water = cold damage types
Fire = fire and acid damage types
Earth = the weapon itself, whence also the piercing, slashing, and bludgeoning damage types
Note, there are different opinions about which element acid belongs to. Acid burns like fire does. However, some systems that I have seen associate acid with water, apparently associating acid with the erosive properties of water, as well as the fact acid is typically a liquid. (Many stories highlight how the water element has magic that can ‘cut’ thru anything. However, during 5e playtests, the ‘emerald ice’ Wizard trope seemed to associate water with both acid and cold, but fell flat, and seemed to disappear from consideration. I get how acid can associate with water.) I have even seen acid associate with earth, in the sense of the mineral and chemical aspects of acid. I lean toward acid damage belonging to the fire element, not only because it burns similar to the way that fire burns (starting at the surface and slowly eating in), but also because resistance to fire is relatively frequent, and acid is a useful backup for a fire specialist to resort to. With these considerations, the acid damage type associates most strongly with the Fire element.