7.82 ct CAVANSITE – INDIA

Cavansite

Cavansite represents the “electric-blue” peak of the vanadium-silicate world. A hydrated calcium vanadium silicate, it is a mineral I have always respected for its “shocking” intensity—a saturation of blue so deep and vibrant that it often appears artificial to the untrained eye. It typically presents as beautiful, “puff-ball” or “rosette” aggregates of radiating acicular crystals, usually perched upon a contrasting matrix of white Stilbite or Heulandite. For the specialist, Cavansite is a prize of vibrant geometry; it offers an orthorhombic structure that prioritizes spherical, “pom-pom” clusters with a vitreous to pearly luster. It is a stone of “lucid energy,” providing a sophisticated, “neon-lagoon” aesthetic that makes it a true “showstopper” for the systematic vault.

The Heritage & Discovery

Historical Significance: Cavansite is a vital species for understanding the complex hydrothermal chemistry of basaltic cavities. Historically, it was considered a major rarity until the spectacular finds in India in the late 20th century. In the world of fine minerals, it is celebrated for its unmatched “electric” hue, which is gifted by the presence of vanadium. It stands as a symbol of clarity and breakthrough, bridging the gap between common zeolites and the elite world of “neon” collector silicates. It serves as a reminder that even within the dark, volcanic basalt of the Deccan Traps, nature can crystallize pockets of “frozen sky.”

Discovery: The name is a clever acronym derived from its chemical components: CAlcium, VANadium, and SIlicate. It was formally described in 1967 based on specimens found in Oregon, USA. However, its discovery in the Wagholi Quarry provided mineralogists with the first clear look at large, “gem-quality” rosettes, turning a formerly obscure mineral into a global icon. My own respect for this material is rooted in its rare “radial” morphology; the way the crystals fan out from a central point to form perfect spheres is a testament to the sophisticated, three-dimensional precision of vanadium-based mineral growth.

Important Mines: The undisputed world capital for the finest “electric-blue” Cavansite is the Wagholi Quarry in Pune, Maharashtra, India. This locality has produced nearly all of the world’s most significant specimens, setting the global benchmark for color and size. I also have a high regard for the historic, smaller occurrences in Columbia County, Oregon, USA. For the vault, I prioritize the Wagholi material for its unmatched “neon-blue” saturation and its spectacular contrast against snowy white Stilbite matrices.

Mineralogical Profile

Description: Cavansite is a calcium vanadium silicate that crystallizes in the orthorhombic system. It sits at a 3 to 4 on the Mohs scale, making it a delicate mineral that must be protected from physical impact. It is characterized by its vitreous luster and its unmistakable “deep azure” to “cyan-blue” color palette.

One of its most identifying traits is its radiating acicular (needle-like) habit and its specific gravity ($SG \approx 2.2$ to 2.3), which makes it feel surprisingly light and airy. It has a moderate refractive index ($n \approx 1.54$ to 1.55) and exhibits a characteristic strong pleochroism, shifting between shades of blue and colorless under polarized light. Because it forms in basaltic vugs, it is almost always found in association with Stilbite, Heulandite, and Apophyllite. When I select a piece for the collection, I look for “isolated” rosettes on a clean matrix, as these highlight the sophisticated, architectural geometry that makes Cavansite a standout for the systematic specialist. It is a light, high-vibration mineral that offers a unique, “electric-calm” beauty unlike any other silicate species.

Chemical Formula: Ca(V⁴⁺O)Si₄O₁₀·4H₂O