interstratification

Interstratification in mineralogy refers to a type of clay mineral structure where layers of two or more different clay minerals are stacked together in a specific, often repeating, pattern. This mixing occurs because different clay mineral layers share similar atomic structures, primarily composed of tetrahedral and octahedral sheets.1

These interstratified structures can be regularly ordered, such as an ABAB... sequence, or randomly mixed. Examples of regularly interstratified minerals include rectorite and corrensite. The mixing ratio of the component layers can vary, leading to a wide range of possible stacking arrangements. The presence of certain interstratified structures can serve as a geothermometer or other geoindicator, providing clues about geological conditions.1

Stratification, in a broader geological context, is the layering observed in most sedimentary rocks and some igneous rocks formed at the Earth's surface. These layers, or strata, differ in rock type or characteristics and can range from millimeters to meters in thickness.23