[Zn8(SiO4)(C8H4O4)6]n (C8H4O4 = isophthalate), synthesized by hydrothermal reaction, possesses a diamondoid framework structure constructed from hexahedron-like Zn8(SiO4) cores and C8H4O4 linkers and remains stable up to 500 degrees C in air, representing the first member of a new class of metallosilicate-organic hybrid materials.