MORDENITE

    Class : Silicates
    Subclass : Tectosilicates
    Crystal system : Orthorhombic
    Chemistry : (Ca,Na2,K2)Al2Si10O24 7H2O
    Rarity : Common

Mordenite belongs to the zeolite group. Like most other zeolites, it is a mineral present in the cavities of volcanic rocks, notably basalts, which is also found as a product of hydration of volcanic glasses and as a newly formed mineral (authigenic) in sediments. its name comes from its locality of discovery : Morden (Nova Scotia, Canada). Mordenite occurs in prismatic crystals, generally very fine acicular, frequently grouped in aggregates or cottony spheres, more rarely tabular. The color is white, sometimes yellowish or pinkish (hematite inclusions). It is synthesized and serves as an absorbent and catalyst.

Main photo : Mordenite from Aurangabad, Maharashtra, India © Cindy Hasler

Mordenite on heulandite from Aurangabad, Maharashtra, India © Jeffrey de Fourestier
Mordenite from Selgil, Berufjord, Iceland © Volker Betz
Mordenite on stilbite from Aurangabad, Maharashtra, India © Jordy Fabre
Mordenite from Stevenson, Skamania County, Washington, USA © Tony Peterson

Mordenite in the World

The most beautiful specimens are 5 cm prisms and 5 cm diameter spherolitic aggregates from the basalt cavities of the Poona region (India), world famous for the quality of its zeolites. Crystals of similar quality have been discovered at South Point, Washington, Berufjord (Iceland) and Shimoda (Honshu, Japan). Good specimens have also been recovered from the type locality : Morden, in the Bay of Fundy (Nova Scotia, Canada).

Mordenite in France

In France, mordenite is known in Velay (Haute-Loire), at the Creuzeval quarry near St-Didier-sur-Beaujeu (Rhône), but also on the Kerguelen islands, in Guadeloupe, Martinique and Piton des Neiges in Reunion island.

Twinning

No twin known for this mineral species.

Fakes and treatments

No fakes recorded for this mineral species.


Hardness : 3 to 4
Density : 2.12 to 2.15
Fracture : Irregular
Streak : White

TP : Translucent to transparent
RI : 1.472 to 1.487
Birefringence : 0.005
Optical character : Biaxial (+/-)
Pleochroism : None
Fluorescence : None

Solubility : Acids

Magnetism : NoneRadioactivity : None