  The equilibrium crystal shape (ECS) of oxygen-covered tungsten micricrystal
is studied as a function of temperature. The specially designed ultrafast
crystal quenching setup with the cooling rate of 6000 K/s allows to draw
conclusions about ECS at high temperatures. The edge-rounding transition is
shown to occur between 1300 K and 1430 K. The ratio of surface free energies
$\gamma(111)/\gamma(211)$ is determined as a function of temperature.
