Amorphous forms [of ice], for example, are found naturally on comets, on asteroids, and the crystalline forms are found on Earth or at least could be made on Earth with enough pressure. Nothing else does this.

The principal reason it transforms is that water is a collection of molecules, H2O, every child learns that.And that bond has the property that as the bonds get stronger when you cool water, the ice expands.

I love ice, when I was in Antarctica many decades ago, I got to see a lot of ice. And the one thing that impressed me -because I love to talk about ice - is that it has a color.

Amorphous forms [of ice], for example, are found naturally on comets, on asteroids, and the crystalline forms are found on Earth or at least could be made on Earth with enough pressure. Nothing else does this.

H2O it's a complicated, three-dimensional, charged object. And one can pack these things in many different ways, a little like playing the child's game of jacks, where those complicated little objects can be thrown together in all different ways.

Normally, you would not call ice a mineral.

Mainly, of course, if you're not an ice climber, where you really need ice, for most people ice is a damn nuisance. And we just can't wait for it to all melt.And it's always a remarkable fact that it takes so long to melt because the temperature of the air can be well above the freezing point, and the ice is still solid there. So for most people, that's the experience.