  If there exists the quark star of maximum mass $\sim 0.7\sol$ as suggested by
recent Chandra observations, we show that the general relativistic collapse of
a neutron star of mass greater than the maximum mass of the neutron star with
angular momentum parameter $q\equiv cJ/GM^2 > 1$ may lead to such a strange
star. Here $J$ and $M$ are the angular momentum and the gravitational mass of
the neutron star, respectively. Under the cosmic censorship hypothesis, such a
star can not be a black hole directly. The jet formed in the soft core might
explode the outer envelope and leave the quark star of mass $\sim 0.7\sol$. The
remnant quark star has $\lesssim 10^{53}$ erg rotational energy so that the
formation of the quark star may be related to the central engine of GRBs. The
detailed numerical simulations are urgent to confirm or refute this scenario.
