  We study the spontaneous emission, the absorption and dispersion properties
of a ${\bf \Lambda}$-type atom where one transition interacts near resonantly
with a double-band photonic crystal. Assuming an isotropic dispersion relation
near the band edges, we show that two distinct coherent phenomena can occur.
First, the spontaneous emission spectrum of the adjacent free space transition
obtains `dark lines' (zeroes in the spectrum). Second, the atom can become
transparent to a probe laser field coupling to the adjacent free space
transition.
