Stilbite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameStilbite
Chemical FormulaNaCa4(Al9Si27O72)·30H2O
Mohs Hardness3.5
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {010}
Fractureuneven
Specific Gravity2.15
Colorswhite, pale orange, pink, yellow, brown
Transparencytransparent
Type LocalityJalgaon District, Maharashtra, India
Mineral GroupSilicates (Zeolite Group)
Usescollector, industrial (adsorbent, catalyst, ion exchange)
Associated Mineralsapophyllite-(KF), calcite, quartz, other zeolites
Raritycommon
Description
This specimen features radiating, sheaf-like aggregates of pale orange to white stilbite crystals, often forming bow-tie or fan shapes. These are intergrown with sharp, colorless to white tabular apophyllite crystals.
Geological Context
Stilbite is a common zeolite mineral typically found in the amygdaloidal cavities of basaltic volcanic rocks, forming as a secondary mineral from the alteration of primary silicates. It can also occur in some metamorphic and hydrothermal environments.
