Which is the only nearly pure metal used for dental casting purposes?

CP titanium, which is classified in four different grades, can technically be considered as an alloy because small percentages of other impurity elements are allowed as specified by a standard that has been established by the American Society for Testing and Materials (ASTM) for each grade. Although it is classified as commercially pure, grade 2 CP-Ti may contain up to 0.10% C, 0.30% Fe, 0.015% H, 0.03% N, 0.25% O, and 0.40% of other elements. Phillips 12th edition page 71