致密长石

例句：

1. 1. The mineralogist studied the crystal structure of the rock.
   矿物学家研究了岩石的晶体结构。
2. 2. The diamond is a rare and valuable gemstone.
   钻石是一种稀有且珍贵的宝石。
3. 3. The quartzite is used in the production of glass.
   石英岩用于生产玻璃。