ptygmatite

例句：

1. 1.The ptygmatite formation is famous for its beautiful blue color.
   片岩层以其美丽的蓝色而闻名。
2. 2.The ptygmatite layer was formed millions of years ago.
   片岩层数百万年前形成。
3. 3. The ptygmatite layer is a valuable resource for mining.
   片岩层是开采的重要资源。