Two proton positions in the very strong hydrogen bond of serandite, NaMn2[Si3O8(OH)] Jacobsen, Steven D. ; Smyth, Joseph R. ; Swope, R. Jeffrey ; Sheldon, Robert I. Abstract Publication: American Mineralogist Pub Date: May 2000 DOI: 10.2138/am-2000-5-613 Bibcode: 2000AmMin..85..745J