  We present Rossi X-ray Timing Explorer, monitoring observations of the
Seyfert 2 galaxy Markarian 3 spanning a 200 day period during which time the
source flux varied by a factor $\sim 2$ in the 4-20 keV bandpass. In broad
agreement with earlier Ginga results, the average spectrum can be represented
in terms of a simple spectral model consisting of a very hard power-law
continuum ($\Gamma \approx 1.1$) modified below $\sim 6$ keV by a high
absorbing column ($N_H\sim 6\times 10^{23}$ \cunits) together with a high
equivalent width Fe-K emission feature at 6.4 keV. The abnormally flat spectral
index is probably the signature of a strong reflection component and we
consider two models incorporating such emission. In the first the reflected
signal suffers the same absorption as the intrinsic continuum, whereas in the
second the reflection is treated as an unabsorbed spectral component. In the
former case, we require a very strong reflection signal ($R ~< 3$) in order to
match the data; in addition variability of both the intrinsic power-law and the
reflection component is required. The unabsorbed reflection model requires a
somewhat higher line-of-sight column density to the nuclear source ($\sim
10^{24}$ \cunits), but in this case the reflected signal remains constant
whilst the level of the intrinsic continuum varies. The latter description is
consistent with the reflection originating from the illuminated far inner wall
of a molecular torus, the nearside of which screens our direct view of the
central continuum source.
