The green garnets in the Wah Wahs are grossular–andradite solid-solution garnets, meaning most specimens fall between the two endmembers:

Grossular (Ca₃Al₂Si₃O₁₂)
Andradite (Ca₃Fe₂Si₃O₁₂)

I beleive this one, is grossular.

Most people think “garnet” is one thing, but there are over a dozen species, including:

Almandine (Fe–Al)
Pyrope (Mg–Al)
Grossular (Ca–Al)
Andradite (Ca–Fe³⁺)
Spessartine (Mn–Al)
Uvarovite (Ca–Cr)
Goldmanite (Ca–V)
Knorringite (Mg–Cr)
Majorite (high-pressure garnet from the mantle)

Each species forms in different geologic environments, which is why garnets are extremely useful to geologists. Because garnet is, hard, dense, and tough it is used as waterjet cutting abrasive, wandblasting media, and abrasive powders. If you’ve ever seen a waterjet slice steel, that cut was powered by garnet.