Final answer:
Quartz is the most common form of crystalline silica, and it is a hard, colorless mineral widely used in numerous applications, including jewelry and electronics.
Step-by-step explanation:
The most common form of crystalline silica is quartz. Silica, or silicon dioxide (SiO2), exists in nature in both crystalline and amorphous forms. Quartz, the crystalline form of silica, is a hard, brittle, and typically colorless mineral that is abundantly found in the Earth's crust.
It is widely used in various applications such as architectural decorations, semiprecious jewelry, and frequency control in radio transmitters.
Quartz can display different colors like the purple hue of amethyst, which is due to trace amounts of iron (Fe3+). When silica is melted and rapidly cooled, it forms fused silica, an amorphous solid. Silica is also the most common component in glass manufacturing, including the creation of stained-glass art that is over a millennium old.