Here's why:

* Chemical Composition: Ice is simply frozen water (H₂O). The chemical formula of water, H₂O, indicates that it's composed of hydrogen and oxygen.

* Mineral Definition: Minerals are naturally occurring, solid, inorganic substances with a defined chemical composition and crystal structure. Ice fits this definition.

* Oxide Group: Oxides are minerals that contain oxygen anions bonded to one or more metal cations. Since ice has oxygen in its chemical formula, it fits within the oxide mineral group.

It's important to note that ice is a very specific oxide mineral. It's not a common rock-forming mineral, but it's still a mineral nonetheless.