Today, scientists have divided true jade into two types, the more valuable jadeite, which is sodium aluminum silicate with a crystalline structure, and hephrite, a calcium magnesium silicate with a fibrous consistency.
到了現代，依科學角度來看，玉在礦物學上，另有專門的定義，只有具備某些特殊成份的礦石，才稱為「玉」，這是狹義的玉。按礦石成分分析，玉又可分為硬玉和軟玉兩大類。硬玉的主要成分是鈉、鋁的矽酸鹽，礦石結構呈緊密的結晶狀。