Primordial

Primordial or the language of elementals is a collection name for the different languages that elementals "speak". There are nine dialects of primordial although they are called dialects they have much more in common with their own languages. When one learns primordial you learn four of the nine dialects although learning new ones is much easier than learning other languages. Sylvan is not included in this and learning it follows the normal rules.
There is no real dialect for mindscape elementals and genasi as most mindscape elementals can communicate telepathically. And psionic genasi with the message cantrip can also communicate with these elementals but not always with all other psionic genasi.

Air	Earth	Etherial	Fire	Lightning	Nature	Radiant	Shadow	Water
Auran	Terran	Quelan	Ignan	Fulgas	Sylvan	Luxan	Umbran	Aquan

Auran, Terran, Ignan, Sylvan and Aquan are more wildly known so the more exotic languages are explained here.

Quelan

Quelan the Ethereal dialect of primordial is composed of very low bass sounds. It takes a lot longer to say things in Quelan than you typical language.

Fulgas

Fulgas the lightning dialect of Primordial is a language that sounds like rolling thunder and crackling sounds with short spikes of explosiveness. The language is very loud and hard on the throat and almost impossible to whisper.

Luxan

Luxan the radiant primordial dialect is a silent language. Many radiant elementals speak by changing the brightness or dimness the light they emit in different rhythms and intensities while moving in a dance like motion. Creatures that can't do this use rhythmic hand motions to communicate while still using the same dance like motion.

Umbran

Umbran is the shadow dialect of Primordial. It is a soundless language of creating shadow images whether by magic or by blocking light with your hands. As such the written and signed language are very similar and learning the written language is enough to understand the signed language.