What Is Clear Quartz? The Most Common Crystal on Earth

Clear quartz is the colorless, transparent form of silicon dioxide, and it's genuinely one of the most abundant minerals in Earth's crust — it forms in nearly every type of rock, from granite to sandstone. Gemologists call flawless, water-clear specimens "rock crystal," a term that predates modern mineralogy.

Because quartz is piezoelectric — it generates a small electric charge when compressed — it's also used in watches and electronics, though that application relies on lab-grown quartz rather than natural crystal. Large natural deposits exist worldwide, with notable sources in Brazil, Madagascar and Arkansas in the US.