When we talk about crystals around here, we’re generally talking about the quartz variety used to make oscillators more stable, or perhaps ruby crystals used to make a laser. We hardly ever talk ...

Chalcedonies include many types of cryptocrystalline quartz ... form beautiful crystals, but the most prized of all are gemstones. Uncut gems often look fairly ordinary–like rocks.

Gem(stone): A precious or semiprecious stone ... leaving behind dazzling crystals like quartz and amethyst. Crystals also form when heat and pressure cause minerals to recrystallize, resulting ...