Dendrite Minerals

A dendrite is a natural tree-like or moss-like formation on, or in, a piece of rock or mineral. A dendritic pattern forms when an element or mineral, starting from a point of origin, migrates and branches outward. A single dendritic branch extends until the mineral reaches a point where growing various new branches is, for some unknown reason, more favourable.

Dendritic crystallization forms a natural fractal pattern. Dendritic crystals can grow into a supercooled pure liquid or form from growth instabilities that occur when the growth rate is limited by the rate of diffusion of solute atoms to the interface.

Dendrite Minerals
Dendritic Agate from India
Photo: LlunaLluviaGems

The surfaces of limestones are often marked by black or red-brown deposits known as mineral dendrites. These are deposits of hydrous iron or manganese oxides formed when supersaturated solutions of iron or manganese penetrate the limestone and are precipitated on exposure to air at the surface. Mineral dendrites have a fractal appearance, but the origin and characteristics of this morphology,

The term "dendrite" comes from the Greek word dendron, which means "tree".

Some examples of dendrite minerals include:

  • Manganese dendrites
  • Copper dendrites
  • Silver dendrites
  • Gold dendrites
  • Iron dendrites
  • Cobalt dendrites
  • Nickel dendrites
  • Zinc dendrites
  • Lead dendrites

Dendrite Minerals
Manganese dendrites on a limestone bedding plane from Solnhofen, Germany.

In paleontology, dendritic mineral crystal forms are often mistaken for fossils. These pseudofossils form as naturally occurring fissures in the rock are filled by percolating mineral solutions. They form when water rich in manganese and iron flows along fractures and bedding planes between layers of limestone and other rock types, depositing dendritic crystals as the solution flows through

How Dendrite Minerals form

Here are some of the ways that dendrites form:
  • When a supersaturated solution of a mineral is cooled, the mineral will precipitate out of solution and form dendrites.
  • When a mineral is dissolved in water and then allowed to evaporate, the mineral will precipitate out of solution and form dendrites.
  • When a mineral is heated, it can sometimes form dendrites.
  • When a mineral is exposed to an electric field, it can sometimes form dendrites.
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