石英 クォーツ クオーツ 석영
The second most common [[gem]] in the world. Used throughout time to make everything from cups to tools and watches. Comes in almost any colors. Usually depicted as clear with a slight white tint.

h4. See also

* [[Citrine (gemstone)|]], the yellow variation.
* [[Chalcedony]], the white and cloudy variation
quartz (gemstone)