Why is ice considered a solid? Isn't it a non-linear viscoelastic FLUID?

In glaciers, compressed ice deforms without breaking. It flows. Not the flow as in a glacier's sliding action over the land, but the ice itself -flowing- (albeit very slowly). I submit that this exception to the rule invalidates the empirical proposition that -all- ice is a solid; and therefore ice's clification as a mineral..LOL! What do you guys think?