Prehnite After Laumontite pseudomorph

This extraordinary specimen is a Prehnite pseudomorph after Laumontite, representing a fascinating geological event where Prehnite has replaced the original Laumontite while perfectly preserving its prismatic crystal shape. At a massive 16 inches across, this specimen is a "mineralogical ghost," offering a rare look at chemical evolution within a volcanic cavity. The piece presents as a large, relatively thin sheet—approximately 1 inch thick—composed of densely layered crystals that maintain the sharp, elongated columnar forms of the original mineral.

Origin & Location

• Mineral Species: Prehnite (Pseudomorph)

• Original Mineral: Laumontite (Zeolite group)

• Primary Locality: Most frequently sourced from the Mumbai-Pune region of the Deccan Traps, India.

• Geological Formation: Formed when Prehnite-rich fluids slowly replaced the original Laumontite crystals in basaltic cavities during late-stage hydrothermal activity.

Specifications

• Weight: 5lb

• Dimensions: Approximately 16 inches at the widest point

• Thickness: Approximately 1 inch

• Color: Characteristic Mint Green to Sage Green

• Crystal Habit: Prismatic columns or "fingers" (mimicking the original Laumontite structure)

Key Features

• Massive Scale & Profile: At 16 inches across with a slender 1-inch profile, this slab offers a high-impact visual field while remaining elegant and display-ready.

• Perfect Pseudomorphism: The replacement process has left the original crystal faces and terminations intact, creating a unique "hollow" or "cast" appearance across the layered sheet.

• Botanical Translucency: The semi-translucent nature of the green Prehnite allows light to penetrate the surface, giving the entire 16-inch formation a soft, inner glow.

• Complex Layered Architecture: Features a dense arrangement of green columns and "fingers," providing a high degree of architectural interest and texture across the entire surface.

Important Notes

• Handling: Due to the thin nature of this 16-inch sheet and the protruding pseudomorph "fingers," this piece requires careful support. Handle with both hands and avoid putting pressure on the delicate crystal terminations.

• Cleaning: Use a very soft, dry brush or a gentle air puffer to remove dust. Avoid high-pressure water, as the internal structure of pseudomorphs can sometimes be more porous than solid crystals.

• Display: This specimen is a premier candidate for a custom-fitted stand or a sturdy, padded easel to highlight its expansive surface area and unique silhouette.