Earth Record
Mineralogy and formation
Basalt cavities in the Deccan Traps can host late hydrothermal minerals whose timing produces extraordinary color contrast. Late hydrothermal fluids moved through vesicles and fractures in Deccan Trap basalt and deposited a sequence of zeolite and associated minerals. Stilbite commonly forms as cream to peach sheaves or bow-tie aggregates, while cavansite arrives as intense blue rosettes of hydrated calcium vanadium silicate.
The contrast is not accidental. It reflects staged mineralization in cavities where changing chemistry allowed one mineral to establish a pale platform before the other produced vivid, radial clusters.
Cavansite itself is relatively soft and hydrated, as is stilbite, so the combination is a display specimen more than a rugged pocket stone. Orthorhombic and monoclinic structures coexist in one compositionally diverse object, and the collector appeal depends on preservation of that delicate relationship. The basalt host is much older and more massive than the cavity minerals it carries. The vug is a small chamber where late-stage chemistry staged a precise visual event.
Somatically the pairing reads as saturation landing on softness. A brilliant blue center appears, but it does not hover unsupported. It sits on a pale framework that makes receiving intensity easier on the body.
The mineral data reinforces that formation story. Cavansite Stilbite carries the chemistry Ca(VO)(Si4O10). 4H2O + NaCa4(Si27Al9)O72. 28H2O, and the stated crystal system is Mixed (Orthorhombic + Monoclinic). Hardness around 3 and specific gravity of 2. 20-2. 30 are not decorative catalog facts. They describe how tightly the structure holds together, how the crystal responds to abrasion, and how much weight the hand expects from a piece of that size.
Luster, color, and origin also preserve clues to environment. Blue material from India (Pune, Maharashtra) reaches the market with a visual identity shaped by local geology, not by a generic stone category.
A specimen therefore carries process in several layers at once: chemistry, symmetry, growth history, and later alteration or treatment where relevant. What emerges from that stack is a stone that can be read physically before any symbolic meaning is assigned.
Mixed (Orthorhombic + Monoclinic) structure
Chemical FormulaCa(VO)(Si4O10).4H2O + NaCa4(Si27Al9)O72.28H2OCrystal SystemMixed (Orthorhombic + Monoclinic)Mohs Hardness3Specific Gravity2.20-2.30LusterVitreous to pearlyColorBlueIMA Statustrade_nameIMA Number1967 (pre-IMA numbered format) Pune district, Maharashtra, India is the world's primary source for gem-quality cavansite-stilbite specimens. The Deccan Traps basalt flows provide the volcanic cavity environment where both zeolite-group minerals crystallize from hydrothermal fluids. The original discovery was in Malheur County, Oregon (USA) in 1967, but Indian specimens dominate the collector market.
India (PuneMaharashtra)
Telling it apart
Cavansite on stilbite is valuable enough that treated blue coatings and glued assemblies show up in the market. The confirming step is check whether blue cavansite rosettes sit naturally on stilbite without glue lines or color bleed. Sellers can lean on color, trade names, or locality mythology, but that one check separates the real material from the easy substitute. Cavansite Stilbite has its own physical signature in the hand and under magnification, whether that means unusual density, a true internal growth pattern, a natural host matrix, or evidence of locality and structure.
Fraud or simple sloppiness matters differently here than it would for a generic tumbled stone. The price gap between natural Indian combinations and altered material is real. A buyer paying for Cavansite Stilbite is paying for a specific geological story, not just a similar color. The blue mineral identification is the price driver, and swapping pentagonite or dyed zeolite for cavansite changes the specimen fundamentally.
Spotting the real thing
Cavansite: vivid blue crystal clusters (distinctive electric blue) on white stilbite matrix. Specific gravity 2. 20-2.
30. Mohs 3-4 (soft). The blue is intense and natural.
If the blue looks painted or is only surface-deep, it is not genuine. Most cavansite-stilbite comes from Pune, India. The combination of electric blue on white is highly distinctive and rarely imitated because the natural material is affordable.
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