If we compare the properties of ice to the five requirements of the mineral definition, we find that it clearly meets the last four. However, requirement #1 presents a problem.

A natural snowflake would be considered to be a mineral because it forms naturally in Earth’s atmosphere. However, an ice cube made in a refrigerator would not be considered a mineral because it was produced by the actions of people.

So, ice is a mineral when it forms naturally, but it is not a mineral when people play a role in producing it.