Stilite

Stilite, more commonly spelled stilbite in mineralogy, is a hydrous sodium–calcium aluminum silicate in the zeolite group. It forms as transparent to translucent crystals and radiating aggregates in vesicles and cavities within volcanic rocks. Stilite belongs to the monoclinic crystal system and typically occurs as tabular or bladed crystals, or in rosette-like clusters. It has a Mohs hardness of about 3.5–4 and a vitreous to pearly luster. The color range includes colorless to white, with pink, orange, or reddish hues occasionally due to impurities; the streak is white.

Chemical composition of stilbite is best described as a hydrated aluminosilicate containing sodium and calcium, with aluminum and silicon tetrahedra in the framework. Its precise formula varies within the zeolite family, reflecting substitutions among Na, Ca, and water content. Stilbite is commonly associated with other zeolites such as natrolite, analcime, and heulandite, as well as quartz and calcite.

Occurrence and distribution are worldwide. Stilite/stilbite forms in zeolite-rich alteration zones of volcanic rocks, especially basalts and related rocks, and in geodes and amygdaloidal cavities. It is widely collected by mineral enthusiasts for its delicate crystal habits, including well-formed tabular crystals and rosettes. While attractive as a specimen mineral, stilbite has limited industrial use due to its softness and water content.

Notes: Stilite is a common misspelling of stilbite; the accepted mineral name is stilbite.