0.30 ct HEULANDITE – INDIA

Heulandite Heulandite is a zeolite that often captures the imagination of mineral collectors with its distinctive, coffin-shaped crystals. While it is a common sight in volcanic cavities, finding a specimen that is transparent and clean enough to facet is a rare event. I have always been fascinated by its pearly luster, especially on the cleavage faces; it has a soft, ethereal glow that differentiates it from the glassier silicates. Working with Heulandite is a delicate process because, like most zeolites, it is heat-sensitive and quite soft. When we successfully facet a piece, we aren't just creating a gem; we are capturing a fragile moment of volcanic history in a structured, brilliant form. The Heritage & Discovery Historical Significance: Heulandite is part of the important zeolite group, minerals known for their "boiling stone" properties and their ability to act as molecular sieves. Historically, it has been a favorite for those documenting the secondary minerals found in basaltic traps. It represents the quiet, slow cooling of volcanic gas bubbles where mineral-rich waters have spent millennia depositing these intricate, pearly structures. Discovery: The mineral was first distinguished from stilbite in 1822 by Henry James Brooke. He named it in honor of the famous English mineral collector and dealer, John Henry Heuland, whose personal collection was one of the most comprehensive of the 19th century. This naming cemented the stone's status as a true collector's mineral from its very inception. Important Mines: The most breathtaking "gem-grade" crystals usually emerge from the legendary Deccan Traps in Maharashtra, India—specifically around Nashik and Pune. Other notable specimens, often in striking shades of red or orange, have been found in the Faroes Islands and Iceland. For faceting, I specifically look for the rare, water-clear or pastel-colored crystals from the Indian basalt pockets, as they offer the best transparency. Mineralogical Profile Description: Heulandite is a hydrous calcium aluminum silicate belonging to the zeolite group. It crystallizes in the monoclinic system, frequently forming "coffin-shaped" or tabular crystals with a vitreous luster that turns pearly on the cleavage planes. It sits at a 3.5 to 4.0 on the Mohs scale, making it a "collector only" gemstone that must be handled with care. Its perfect cleavage and sensitivity to heat mean the lapidary must use a light touch and low-speed polishing to prevent the stone from fracturing or dehydrating. Chemical Formula: (Ca,Na)_2-3Al₃(Al,Si)₂Si₁₃O₃₆·12H₂O