Pristine, a.
Etymology: [L. pristinus, akin to prior: cf. F. pristin. See Prior, a.]
Belonging to the earliest period or state; original; primitive; primeval; as, the pristine state of innocence; the pristine manners of a people; pristine vigor.
Shades of meaning
Fernald has no entry of its own for pristine; he lists it under primeval.
Where he writes about it:
Pristine is an elegant word, used almost exclusively in a good sense of that which is original and perhaps ancient; as, pristine purity, innocence, vigor. — from primeval