Kivistuma

Kivistuma is a Finnish term that translates to "petrification" or "calcification" in English. It refers to the process by which organic material, such as bone or wood, is gradually replaced by minerals. This transformation typically occurs over long periods, often in geological settings where mineral-rich water seeps into the porous structure of the organic matter. As the water evaporates or its chemical composition changes, dissolved minerals precipitate out and fill the spaces previously occupied by the original material.

This process is a key mechanism in the formation of fossils. When an organism dies and is rapidly buried in sediment, it can become preserved through kivistuma. The original organic molecules decay, but the mineral infill retains the shape and even some of the microscopic details of the original structure. Different types of minerals can be involved, leading to various types of fossilization. Silicification, where silica replaces the organic material, is a common form of kivistuma that results in petrified wood. Carbonatization, involving calcium carbonate, is another significant process.

While primarily associated with fossilization, kivistuma can also occur in more recent biological contexts, such as the formation of dental calculus (tartar) on teeth or the pathological calcification of soft tissues in living organisms. In these cases, mineral deposits accumulate within or on biological structures, often due to changes in local chemistry or the presence of specific ions. The term emphasizes the mineral replacement aspect of these phenomena.