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What we have here is a massive and incredibly rare example of a Limonite pseudomorph after Marcasite, featuring the highly sought-after "Jack Straw" crystal habit.
"Jack Straw" formations are famous for their chaotic, haystack-like arrangement of elongated crystals. Because this structure creates so many open voids, these specimens are usually found broken or crumbled. Finding a piece of this magnitude (over 1 lb) intact with the delicate lattice structure preserved—is exceptionally rare.
Key Features:
Pseudomorph: The chemical composition has altered to Limonite (iron oxide) while perfectly preserving the original Marcasite crystal shape.
Structure: Distinct, sharp crisscrossing blades (Jack Straw) with excellent definition.
Size: A true "Cabinet" sized specimen that dominates a display shelf.
Provenance: Fortress Keep Mine Jefferson County MO.
This is a top-tier collector's piece for those who appreciate pseudomorphs and structural mineralogy. It ships securely packed to ensure it arrives in this exact pristine condition.
Seller Note:
This piece is a true survivor. "Jack Straw" formations are notoriously fragile, and finding a 1-pound+ cluster with the lattice perfectly preserved is rare. A fantastic addition for structural mineral collectors.
