Forerunner Foray — Andre Norton

It was on Ziantha's foray into the ancient Forerunner worlds of hidden treasure and wisdom that she was inexorably drawn to the throbbing green stone. It was irresistibly attractive, and as soon as she possessed it she felt compelled to unlock its most hidden secrets.

But such brazen curiosity would carry a deadly price for Ziantha. For although she was a highly skilled sensitive trained in mind-touch, her dangerous quest thrust her into a stranger's identity, leaving her trapped in the Forerunner's turbulent, alien past.

Suddenly pushed into a desperate race, not only against time, but against unknown enemies with harrowing powers, Ziantha must fight to keep from being transported even farther back to another mysterious identity. She must find a way to return to her own true self...