Class : Silicates
    Subclass : Phyllosilicates
    Crystal system : Monoclinic
    Chemistry : (Ca,Na)_0.3(Mg,Fe)₃(Si,Al)₄O₁₀(OH)₂ 4H₂O
    Rarity : Common

Saponite is a magnesium hydrated phyllosilicate of the smectite group. It is a silicate alteration mineral that is generally formed by alteration of basic and ultrabasic igneous rocks, but can also result from hydrothermal alteration of plagioclase in hydrothermal deposits, sometimes in skarns. Its name comes from the Latin sapo (soap) in allusion to the soft and greasy appearance of its aggregates in small scales. It occurs like most clays in earthy, compact, unctuous masses. The crystals are microscopic, pseudohexagonal in appearance. It is a white to yellowish clay, sometimes colored light yellow, greenish or reddish. Saponite is, with beidellite, montmorillonite and nontronite, one of the main constituents of bentonite.

Main photo : Sampleite from La Farola Mine, Atacama, Chile © Uwe Haubenreisser

No twinning known for this mineral species.

No fakes listed for this mineral species.