天然水晶(rock crystal）是一种石英结晶体矿物，它的主要化学成份是二氧化硅，化学式为SiO2，别名水精、水碧、水玉。发育良好的单晶为六方锥体，所以通常为块状或粒状集合体。一般为无色、灰色、乳白色，含其他矿物元素时呈紫、红、烟（茶）、黄、绿等。
天然水晶的英文是 rock crystal，白水晶英语是Clear Quartz。
天然水晶英语介绍
Quartz is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra,with each oxygen being shared between two tetrahedra,giving an overall chemical formula of SiO2.Quartz is the second most abundant mineral in Earth's continental crust,behind feldspar.[7]
Quartz crystals are chiral,and exist in two forms,the normalα-quartz and the high-temperatureβ-quartz.The transformation fromα-quartz toβ-quartz takes place abruptly at 573°C(846 K).Since the transformation is accompanied by a significant change in volume,it can easily induce fracturing of ceramics or rocks passing through this temperature limit.
There are many different varieties of quartz,several of which are semi-precious gemstones.Since antiquity,varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings,especially in Eurasia.
