IDM-1 is a new silica zeolite with an ordered and well-defined framework constructed by alternating pentasil layers and interrupted layers, giving rise to an intersecting system of straight medium pores and undulating extra-large lobed pores. This unique structure was solved by rotation electron diffraction and refined against synchrotron powder X-ray diffraction data. Despite the presence of both Si(OSi)(3)(OH) and Si(OSi)(2)(OH)(2) sites, this new zeolite presents high thermal stability, withstanding calcination even to 1000 degrees C. The location of defects at specific sites of the structure results in alternating hydrophobic SiO2 and hydrophilic SiO(2-x)(OH)(2x) intracrystalline regions. This peculiar combination of intersecting medium and extra-large pores and alternating regions of different chemical character may provide this zeolite with unique catalytic properties.