[gwillen]

At some point it becomes silly to keep adding 'phases of matter'. And if you want to be exhaustive, don't forget the other oddball types: the high-density states like neutronium, the high-energy states like quark-gluon plasma, etc.

[stephengillie]

You've got a good point, and there's lots of exotic types and in-betweens on Wikipedia which I didn't list. My list was to point out that we've named more than the 3 classical states of matter.