'Crystal' in the Bible

And before the throne there was a sea of glass like unto crystal: and in the midst of the throne, and round about the throne, were four beasts full of eyes before and behind.

Having the glory of God: and her light was like unto a stone most precious, even like a jasper stone, clear as crystal;

And he shewed me a pure river of water of life, clear as crystal, proceeding out of the throne of God and of the Lamb.