Recently, I was checking on [this question][1] and I was thinking of the name of the compound $\ce{FeS2}$. Later I checked the name in the answer to be **iron disulfide**. I found the following statement in the comments section:

> Persulphide? Disulphide is ok here but per- not really.

The answerer actually named $\ce{FeS2}$ to be **iron persulfide** but later changed to **iron disulfide** after responding to the comment.

I checked the google and found [the wikipedia article of marcasite][2] and referred its name to be **iron(II) disulfide**. But why? Why not iron persulfide? It contains the $\ce{S2^2-}$ ion which is named **disulfide** anion. Why not persulfide anion (as per analogy to peroxide anion $\ce{O2^2-}$)?

In a group, compound names are named similarly to follow a certain fashion/trend. For e.g. *methane, silane, germane* (group 14). So, why $\ce{H2O2}$ is hydrogen peroxide and $\ce{H2S2}$ is hydrogen disulfide? Why it is not named hydrogen persulfide by analogy? 
 
Related:
https://chemistry.stackexchange.com/questions/53533/why-is-h2o2-named-hydrogen-peroxide


  [1]: https://chemistry.stackexchange.com/questions/59404/how-can-fes2-be-the-formula-of-iron-sulphide-and-cac2-be-the-formula-of-calcium
  [2]: https://en.wikipedia.org/wiki/Marcasite