Fused silica is an engineering-quality, amorphous version of quartz.

Source: http://www.makeitfrom.com/material-data/?for=Fused-Silica-Fused-Quartz

yes. back in the 15th century when alchemy was popular scientists found out the mineral quartz is piezo electri and so is fused quartz

Fused quartz. The quartz has been heated over a fire.

The density of quartz is around 2.6, meaning that it weighs 2.6 times as much as an equal volume of water.

There are countless uses for quartz. The colorful transparent varieties are polished into gems. Opaque varieties are processed into ornamental items or building materials. Very pure quartz sand deposits are mined for the many items that use silicon, like computer chips.