Apophyllite
Image: Raimond Spekking (CC BY-SA 4.0)
Mineral NameApophyllite
Chemical FormulaKCa4(Si8O20)(F,OH)·8H2O
Mohs Hardness4.5
Crystal Systemtetragonal
Lustervitreous
Streak Colorwhite
Cleavageperfect on {001}
Fractureuneven
Specific Gravity2.35
Colorscolorless, white, green, pink, yellow
Transparencytransparent
Type LocalityIndia
Mineral GroupPhyllosilicates
Usescollector, ornamental
Associated Mineralsstilbite, heulandite, calcite, quartz, prehnite
Raritycommon
Description
This specimen features a cluster of well-formed, transparent to translucent apophyllite crystals, exhibiting a blocky to pyramidal habit and a vitreous luster. The crystals are predominantly colorless or very pale, showcasing their characteristic form.
Geological Context
Apophyllite typically forms as a secondary mineral in the vesicles and cavities of basaltic volcanic rocks, often associated with zeolites. It crystallizes from hydrothermal solutions circulating through these rocks during the late stages of volcanic activity.
