Matthew Poole and continuators on Deuteronomy 33:15

15 And for the chief things of the ancient mountains, and for the precious things of the lasting hills .

(i. e.) The excellent fruits, as Grapes, Olives, Figs, &c. which delight in Mountains, growing upon, or the pretious Minerals contained in, their mountains and hills called antient and lasting, i. e. such as have been from the beginning of the world, and likely to continue to the end of it, in opposition to those hills or mounts which have been cast up by the wit of man: