  We present a two-flavour linear sigma model with global chiral symmetry and
(axial-)vector mesons as well as an additional glueball degree of freedom. We
study the structure of the well-established scalar resonances f0(1370) and
f0(1500): by a fit to experimentally known decay widths we find that f0(1370)
is predominantly a \bar{q}q state and f0(1500) is predominantly a glueball
state. The overall phenomenology of these two resonances can be well described.
Other assignments for our mixed quarkonium-glueball states are also tested, but
turn out to be in worse agreement with the phenomenology. As a by-product of
our analysis, the gluon condensate is determined.
