rock crystal
transparent quartz

But my guess would be rock crystal - transparent quartz.

You know, if that really is rock crystal, it would be worth a fortune.

He found a rock crystal and pulled it out instead.

Windows of glass, rock crystal, and colored minerals were set at every level on the wall.

More and more antique rock crystal is coming on view now.

The quality of rock crystal carving seems to have deteriorated in Europe from the 18th century to the 20th.

Also on display is a collection of artworks made from rock crystal.

The feeling the little rock crystals left was not pleasant.

They wanted to sell us little pieces of rock crystal.

Behind the chrome plates is revealed a wall of rock crystal.