Hierarchy classification:

1. top of the aat hierarchies
2. Materials Facet
3. Materials (hierarchy name)
4. materials (substances)
5. [materials by form]
6. [materials by physical state]

Anotations

Scope note:

Any of various frozen or solidified forms of substances (including water) that are liquid, gaseous, or volatile under normal conditions on earth; the term is used particularly in astronomy for such materials, which are present in the nuclei of comets, in planets, and in other celestial objects.Often used with a modifying word specifying the substance, such as ammonia ice, methane ice, water ice, etc.