摘要

<正>在加利福尼亚州科林加的深山中,人们可以挖掘到地球上最稀有的宝石。主题语境:人与自然篇幅:338词建议用时:7分钟1Deep in the hills of Coalinga, California, members of the public can dig for benitoite, the rarest gem (宝石) on Earth. The Benitoite Mining Company transports dirt directly from a hidden mine to an empty field on the site of what was once a prison.