Sheldrickite occurs in a marble xenolith in the nepheline syenite intrusive unit close to a large unit of hornfels. The crystals were found in a cavity between shortite crystals and as flakes in thin seams between crystals of shortite. This mineral assemblage is thought to be a late stage hydrothermal infilling. Sheldrickite does not display any fluorescence. The specimens were collected in 1991 and only 60 mg are known to exist which makes it a very rare mineral.
Color is colorless to white.
Luster is vitreous to silky. Diaphaneity is opaque. Fracture is uneven. 3 Streak is white. Associated Minerals include aegirine, arfvedsonite, calcite, fluorite, galena, kogarkoite, leucosphenite, microcline, molybdenite, pectolite, polylithionite, schairerite, sphalerite, thenardite and thermonatrite.