Stilbite
Image: Didier Descouens (CC BY-SA 3.0)
Mineral NameStilbite
Chemical FormulaNaCa4(Si27Al9)O72·28H2O
Mohs Hardness3.5
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {010}
Fractureuneven
Specific Gravity2.15
Colorswhite, cream, pale brown
Transparencytranslucent
Type LocalitySaint-Christophe-en-Oisans Isères France
Mineral GroupSilicates
Usescollector
Associated Mineralsheulandite, apophyllite, quartz, calcite
Raritycommon
Description
The image displays a specimen of stilbite featuring a dense aggregate of small, radiating, off-white to pale brown crystals, forming a botryoidal or sugary texture.
Geological Context
Stilbite commonly forms as a secondary mineral in the amygdaloidal cavities of basaltic and other volcanic rocks, and can also be found in hydrothermal veins and some metamorphic environments.
