Hyaline

Hyaline was a milky or white form of quartz and was usually cut as plates for inlays or cut cabochon and mounted in a silver setting.

Description
The milkiness of these ornamental stones was caused by tiny droplets of water or carbon dioxide trapped in the crystals. Some specimens contained flecks of gold. A typical stone had a base value of 10 gp.

Powers
Hyaline was sensitive to magic and would give off a blue glow whenever magic was activated, triggered, cast, or passed within 20 feet (6.1 meters) of a hyaline gem.