  Tin (II) sulfide (SnS) is a layered mineral found in nature. In this paper,
we study the two-dimensional form of this material using a combination of
\emph{ab initio} calculation and $\mathbf{k}\cdot\mathbf{p}$ theory. In
particular, we address the valley properties and the optical selection rules of
2D SnS. Our study reveals SnS as an extraordinary material for valleytronics,
where pairs of equivalent valleys are placed along two perpendicular axes, can
be selected exclusively with linear polarized light, and can be separated using
non-local electrical measurements.
