AM_Penkvilksite Formula: (Ti.9 Zr.1) Si4 Na2 O13 H4 Name: Penkvilksite Unit cell: 16.3721 8.7492 7.402 90.0 90.0 90.0 , V=1060.28 Space group: PNCA (60)

Merlino S , Pasero M , Artioli G , Khomyakov A P , American Mineralogist , 79 (1994) p.1185-1193, Penkvilksite, a new kind of silicate structure: OD character, X-ray, single-crystal (1M), and powder Rietveld (2O) refinements of two MDO polytypes, Note: polytype 2O