nummulite

例句：

1. 1.The nummulite is a rare mineral found in the Earth's crust.
   这种矿物是地球地壳中的一种罕见矿物。
2. 2. The nummulite has been used in ancient civilizations for its healing properties.
   这种矿物在古代文明中被用于其治疗属性。
3. 3. The nummulite was discovered by a team of scientists during their expedition to Antarctica.
   这个矿物是由一支科学家团队在南极探险期间发现的。