Two new quaternary chalcogenides, La4FeSb2S10 and La4FeSb2Se10, have been synthesized from the stoichiometric mixture of elements by solid-state reactions at 1100 degrees C. The compounds crystallize in the orthorhombic space group Pbcm with a = 15 066(4) angstrom, b = 7.590(2) angstrom, c = 13.341(4) angstrom, and Z = 4 and a = 15.596(5) angstrom, b = 7 869(2) angstrom, c = 13.960(4) angstrom, and Z = 4, respectively. These structures represent an unique three-dimensional network, in which SbQ(3) trigonal pyramids (Sb-S < 2.60 angstrom, Sb-Se < 2.80 angstrom) are connected via a relatively weak Sb-Q bond (Sb-S approximate to 2.90 angstrom, Sb-Se approximate to 3.00 angstrom) in a novel teeter-totter (SbQ(4))(n) chain motif. The theoretical studies confirm the Sb-Q bonding interactions within such teeter-totter chains. Their optical band gaps are measured to be 1 00 and 0.85 eV. At room temperature, their electrical conductivities are about 10(-4) S/cm. Both compounds display antiferromagnetic interactions between Fe centers, and their effective magnetic moments are 5.25 and 6.17 mu(B), respectively.