bray stone

例句：

1. 1. The geologists found a braystone that could be used to study theformation of the earth's crust.
   地质学家发现了一块可以用来研究地球地壳形成的岩层。
2. 2. The bray stone was discoveredin the desert, and it has beenused as a marker for centuries.
   这块岩层在沙漠中被发现，几个世纪以来一直被用作标记。
3. 3. The bray stone isa valuable resource for mineral exploration.
   这块岩层是矿物勘探的重要资源。