Dendritic Jasper

Dendritic Jasper is an opaque jasper containing dendrites, branching, plant-like inclusions of manganese and iron oxides that grow in fractal patterns through the stone. The dendrites look like ferns, trees, or frost on a window, but they are purely mineral, not fossilized plants.

The contrast between a pale cream or tan silica body and the dark feathery dendrites makes this a favorite scenic stone. It overlaps in appearance with dendritic agate, the difference being jasper's opacity versus agate's translucence.

The host jasper forms when silica precipitates as a dense microcrystalline quartz mass within sediment or volcanic rock. The dendrites form separately and later, when manganese- and iron-rich solutions seep along tiny fractures and bedding planes in the stone.

As these metal-oxide solutions crystallize in two dimensions along the cracks, they branch repeatedly into the characteristic fern or tree shapes. The process is a mineral growth pattern driven by diffusion, not biological growth, which is why dendrites can appear in stones of any geologic age.

Look for a light-colored opaque jasper marked with dark, finely branching fern- or tree-like figures.

• Hardness: 6.5-7; scratches glass.
• Luster: waxy raw, vitreous when polished.
• Streak: white (the body); dendrites are too thin to streak.
• Look-alikes: dendritic agate has the same dendrites but is translucent; moss agate shows green clumped inclusions rather than tree-like branches; true plant fossils show cellular structure under magnification while dendrites do not.

Dendritic Jasper is a sought-after lapidary stone for cabochons, slabs, and pendants where the dendrites can be displayed like miniature landscapes. Collectors value pieces with crisp, well-developed tree patterns.

Durable at near 7 Mohs, it holds a polish and wears well in jewelry. In metaphysical lore dendritic stones are associated with growth, nature, and stability, beliefs that are spiritual rather than scientifically established.