Emergent 1/3 magnetization plateaus in pyroxene CoGeO3

Despite the absence of an apparent triangular pattern in crystal structure, we observe unusually well pronounced 1/3 magnetization plateaus quasi one-dimensional Ising spin chain compound CoGeO$_3$ which belongs to class pyroxene minerals. We succeeded uncovering detailed microscopic structure plateau phase by means neutron diffraction. observed changes initial antiferromagnetic zero-field that are resembling a regular formation "domain wall boundaries", resulting kind modulated magnetic with 1/3-integer propagation vector. The net ferromagnetic moment emerges at these walls" whereas two third all alignments can be still preserved. propose model on basis anisotropic frustrated square lattice explain observations.