Malliliite

Malliliite is a term used in Finnish to describe a lithological unit characterized by the presence of mallite. Mallite is a rare mineral, a hydrous magnesium carbonate hydroxide, with the chemical formula Mg5(CO3)(OH)6·2H2O. It is typically found in serpentinite rocks, often associated with hydrothermal alteration processes. These serpentinite occurrences are commonly derived from the alteration of ultramafic igneous rocks.

The geological context in which malliliite is found provides clues about the conditions under which it forms. The presence of magnesium, carbonate, and hydroxide components suggests an environment rich in these elements, likely influenced by the interaction of water with magnesium-rich rocks. Serpentinization, the process of altering olivine and pyroxene minerals to serpentine, is a key precursor event that can create the necessary mineralogical and chemical environment for malliliite precipitation.

While malliliite is not a widespread or economically significant mineral, its discovery in certain geological settings is of interest to mineralogists and geologists studying alteration processes and the geochemistry of ultramafic rocks. Its rare occurrence makes it a subject of study for understanding unusual mineral formation pathways. The exact geological conditions and specific environments favoring malliliite formation are still areas of ongoing research.