Laser cooling and trapping of 199Hg atoms has been shown to be attainable in a macroscopic, purely optical trap formed by a bichromatic field. In the low-intensity regime of light waves, analytical expressions for the force on atoms were derived, allowing us to estimate the depth of the macroscopic potential and its dependence on field parameters. Within the semi-classical approximations, numerical analysis was performed to demonstrate the high efficiency of laser cooling and trapping of mercury atoms, which is comparable to magneto-optical traps. The proposed purely optical trap allows mercury atoms to be cooled directly from the hot fraction and to be localized in a minimum of macroscopic potential, forming a sub-millimeter cloud of cold atoms with a sub-Doppler temperature ≃ 20 µK. In contrast to magneto-optical trap, the proposed scheme uses no magnetic field, which is significant for applications requiring the minimization of magnetic shifts in the probing area. The achieved results are of great interest for further development of quantum sensors and atomic clocks.