Unpredictable, erratic or fickle; mercurial.
The metal mercury.
An amalgam of mercury and tin applied to the backs of mirrors, quicksilvering.
To overlay with quicksilver.
To treat with quicksilver.
Subject to changing and unpredictable emotional states; moody, capricious.
Of, related to, or caused by temperament.
User-unfriendly, unstable, that is complicated or has poorly written instructions and is subsequently difficult to operate.