She continued to bang away on her keyboard, the smile etched on her face.
The faces are often etched or corroded.
A similar distribution of electric charges is produced when a crystal is subjected to pressure; quartz being thus also piezo-electric. Etched figures, both natural and artificial (in the latter case produced by the action of hydrofluoric acid), on the faces of the crystals are in accordance with the symmetry, and may serve to distinguish leftand righthanded crystals.
The latter are in fact little microscopes carrying a vernier etched on glass, in lieu of a filar micrometer.
He was standing at the edge of the kitchen, a bouquet of wildflowers in one hand and concern etched in that delicious chocolate gaze.