  We calculate the g-factor of the 6s6p 3P0 state of 199 and 201 mercury
isotopes using a relativistic high-precision all-order method that combines the
configuration interaction and the coupled-cluster approaches. Our values
$g(199Hg) = -0.9485(49)*10^{-3}$ and $g(201Hg) = -0.3504(18)*10^{-3}$ are in
agreement with the experimental measurements within the 0.5% theoretical
uncertainty. We also calculate the hyperfine quenching rate of the 6s6p 3P0
state in 199Hg and 201Hg and determine its lifetime to be 1.3 and 1.9 s,
respectively.
