Sheldrickite is a sodium calcium carbonate fluoride mineral, named in honor of George M. Sheldrick, former Professor of Crystallography at the University of Göttingen in Germany.
[2] A series of plutons is aligned along the St. Lawrence Valley for almost 150 km eastward from Oka to Megantic.
[2] The associated species of Sheldrickite include pectolite, microcline, arfvedsonite, aegirine, polylithionite, calcite, fluorite and minor molybdenite, leucosphenite, thenardite, thermonatrite, sphalerite, galena, schairerite and kogarkoite.
[2] The second habit occurs as a radiating thin white silky flakes to fibrous masses up to 2 mm wide.
[4] The precession photographs show sheldrickite to be hexagonal with a diffraction symmetry of 6/mmm, with space-group choices P6222 and P6422.
[2] The Sodium (Na) polyhedron, with its 8-fold coordination, fits the compressed octahedron that is modified by the removal of one edge.