Formula: Na2Zr(Si3O9).2H2O Cyclosilicate (ring silicate), benitoite group. Dimorph of gaidonnayite. Forms a solid solution with calciocatapleiite.
Specific gravity: 2.65 to 2.9
Hardness: 5½ to 6
Streak: White to pale yellow
Colour:Dark brown, reddish brown, flesh red, yellowish red,colourless, light grey, beige to tan, light yellow, orange, light blue

Plutonic igneous environments

Catapleiite occurs in pegmatites, typically as an alteration product of eudialite, and in syenite and nepheline syenite, associated with zircon, leucophanite, rinkite, eudialite, epididymite, lavenite, astrophyllite, sodalite, natrolite, analcime and aegirine.

At Strange Lake, Quebec-Labrador, Canada, catapleiite occurs as pseudomorphs after dalyite and vlasovite.

At Narsarsuk, Greenland, catapleiite has been found in syenite.

At the type locality, LĂ„ven, Vestfold, Norway, catapleiite occurs in a nepheline syenite pegmatite, associated with zircon, tritomite-(Ce), mosandrite-(Ce), leucophanite and aegirine. The catapleiite-bearing rock is free of eudialite-eucolite (variety of ferrokentbrooksite), but elsewhere at this locality grains of eudialite are common showing alteration to eucolite (variety of ferrokentbrooksite).

At Magnet Cove, Hot Spring county, Arkansas, USA, catapleiite is found in dike rocks made up of feldspar and aegirine, with accessory titanite and secondary natrolite. The catapleiite specimens are free of eudialite and eucolite (variety of ferrokentbrooksite). It appears that eudialite alters to eucolite (variety of ferrokentbrooksite) and then to catapleiite, by hydration, with the catapleiite forming at about the same point as the zeolites.

At Buck Hill, Augusta county, Virginia, USA, catapleiite is asssociated with synchysite-(Ce).

Common impurities: Ca,Fe