an impure form of quartz consisting of banded chalcedony; used as a gemstone and for making mortars and pestles
"She carefully polished the rough piece of agate until its concentric bands shimmered, then set it aside to be cut into rings."
A semi-pellucid, uncrystallized variety of quartz, presenting various tints in the same specimen, with colors delicately arranged in stripes or bands, or blended in clouds.
"She carefully sliced open the rough stone to reveal an agate with swirling bands of red and white that seemed to move under the light."
On the way; agoing.
"The train was agate when we finally boarded it after missing our connection."