When water rich in manganese and iron oxides flows through fissures and cracks in rocks or minerals, these metallic elements are sometimes deposited within the crystal structures they encounter. Over millions of years and cooling conditions, the tiny particles that were deposited into the host material solidify, crystallizing into a branch-like imprint. This is very similar to the way that snowflakes form; when liquid water is cooled, it forms into dendritic patterns as the water molecules freeze and crystallize, growing upon each other in intricate and beautiful forms.