稀土为什么叫稀土？

稀土是一种元素周期表中的镧系元素，包括镧（La）、铈（Ce）、镨（Pr）、钕（Nd）、钷（Pm）、钐（Sm）、铕（Eu）、钆（Gd）、铽（Tb）、镝（Dy）、钬（Ho）、铒（Er）、铥（Tm）、镱（Yb）和镥（Lu）等15种元素。这些元素在地球上的储量非常有限，但却具有广泛的用途和重要的战略意义。英文翻译对照：

Why are rare earth elements called "rare earths"?

Rare earth elements refer to the lanthanide elements in the periodic table, including lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). These elements have limited reserves on Earth but have a wide range of uses and important strategic significance.

英文翻译对照：Rare earth elements refer to the lanthanide elements in the periodic table, which include 15 elements: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). These elements have limited reserves on Earth but are widely used and have important strategic significance.