Mineral Species: Stellerite

Chemical Formula: CaAl2Si7O18·7(H2O)

Chemical Name: Hydrated Calcium Aluminium Silicate

Mineral Class: Zeolite Silicate

Mineral Notes: Stellerite is related to the much more common zeolite Stilbite. It differs because of the substitution of aluminum for silicon in the framework stucture. Stilbite has an extra aluminum for every seven silicons and therefore requires a sodium to balance the chemical charge. Like Stilbite, Stellerite crystals can aggregate together to form a structure resembling wheat sheafs. Stellerite's structure has a typical zeolite openness that allows large ions and water to reside and move around inside the framework.

Description: Orange-pink Stellerite on matrix. The mineral forms hundreds of small spherules which are often fused into larger aggregates. Both the mineral and the matrix are very lustrous, making this a very attractive display specimen.

Location: Rossing Mine, Namibia.