Aragonite (White)

White Aragonite, also known as Cave Calcite, cave popcorn and coralloids), is a calcium carbonate mineral and a variety of Aragonite that crystallizes in long spikey crystals and a large botryoidal pattern resembling a cloud formation. The color can range from bright white to a dark brown and can range in size from a few inches to over a foot tall. Aragonite and calcite are both calcium carbonates with the same chemical formula (CaCO3), but different crystal structures and symmetries. As calcium carbonates, both have the tendency to form speleothems in limestone-rich environments like caves. For clarification, a speleothem is a geologic formation that occurs as carbonates build up through various types of depositing along the walls of cave systems.

Cave calcite forms underground from groundwater deposition. As water seeps through limestone and CO2 is lost over time, these minerals will precipitate into a residue that looks like bulbous masses encrusting a surface. Cave calcite may also form when groundwater evaporates, but will present as a more creamy white that resembles actual popcorn. While it often forms as stalactites and stalagmites, it can also form unique, branching, tree-like structures. These beautiful formations are sometimes known as ‘Floss Ferri’ (flowers of iron) and frostwork.