Zeolite
Mineral NameZeolite
Chemical Formula(Na,K,Ca)x[AlxSiyO2(x+y)]·nH2O
Mohs Hardness3.5
Streak Colorwhite
Cleavagevariable, often distinct in one or two directions, sometimes poor or absent
Fractureuneven to conchoidal
Specific Gravity2.2
Colorswhite, grey, colorless, pink, red, yellow, green, blue
Transparencytransparent to translucent, opaque in massive forms
Type LocalityWorldwide, common in volcanic regions (e.g., Deccan Traps, Iceland, Italy, USA)
Mineral GroupSilicates (Tectosilicates)
Usesadsorbents, catalysts, ion-exchangers, water purification, agriculture, construction, collector specimens
Associated Mineralscalcite, apophyllite, prehnite, quartz, feldspar
Raritycommon
Description
Two samples of zeolite are shown; one is a larger, off-white, blocky piece with a somewhat earthy texture, and the other is a smaller, light grey, porous, and irregular piece resting on top, with a penny for scale.
Geological Context
Zeolites typically form in the vesicles and cavities of basaltic and other volcanic rocks, or as alteration products of volcanic ash in sedimentary environments, under low-temperature hydrothermal conditions.
