volcanic sand

• 火山沙,火山砂

volcanic sand的用法和样例：

例句

1. In the black volcanic sand was left the trails of their tiny fin prints.
   它们在黑色的火山沙上只留下了小小的鳍状印迹。
2. The sand, which is formed by dark green crystals called olivine, is brought to the surface by volcanic activity.
   这片绿沙由称为橄榄石的墨绿色结晶体形成，被火山活动带到地表。