1. Chemical elements with low abundance in the Earth's crust, including rare earth elements (lanthanides and actinides) and other scarce elements
Rare elements are essential for modern technology and renewable energy applications.
Os elementos raros são essenciais para a tecnologia moderna e aplicações de energia renovável.
2. In chemistry and materials science, elements that occur in small quantities and are difficult to extract or process
The mining of rare elements is economically challenging and environmentally sensitive.
A mineração de elementos raros é economicamente desafiadora e ambientalmente sensível.