Marcasite Plume Agate
SI02 + FeS2
Clouds with silver linings
Actually, more like Plumes with gold linings. Marcasite can be seen in this close-up picture of rough stone in the upper edge above the white clouds appearing like dark plumes with metallic flashes. Marcasite is a mineral consisting of Iron Sulfide (FeS2). It is related to Pyrite (Fools Gold) though instead of having a cubic structure, Marcasite presents itself in crystal structure.
Lightning in a Bottle
This Graveyard Point Plume Agate from Eastern Oregon polished up with fantastic spires of Marcasite in its dark plumes. The crystal structures are very small so instead of distinctly seeing them, like druzy quartz crystals, it looks more like someone dropped glitter into the agate.
Sometimes the Marcasite is so densely concentrated that the Agate appears black. When this piece is in full sun, the Agate turns a rich olive green radiating with all the facets of Marcasite crystals blazing like an inner sun.
Tones in the Stone
With varying degrees of inclusion, Marcasite wanders through this Graveyard Point Plume Agate adding glimmer to the vibrant red and toning it down through maroon to purple in areas of higher content.
The Marcasite appears in the stones in such a variety of ways that no two stones are the same. From gradients with an ombre’ effect to detailed plumes, dendrites, and lacy inclusions, it always adds an exciting glow to stunning gemstones.