CALCITE – Flower-Shaped Cluster, 100+ UV-Fluorescent Crystals, Iraí, Brazil

This is an exceptional museum-size calcite specimen from Iraí, in the state of Rio Grande do Sul, Brazil, one of South America's most celebrated basalt geode districts. The piece is entirely covered by more than 100 individually formed calcite crystals, arranged so densely and radially that they naturally recreate the appearance of a blooming flower — a striking effect that collectors specifically seek out from this locality. Among the many crystals, at least six exceptional individuals exceed 17 cm in length, an unusually large size for calcite of this style and quality.

The crystals themselves display the classic elongated, stepped scalenohedral habit typical of Iraí calcite, with lustrous faces and pointed terminations that catch the light beautifully across the entire cluster. Their tone ranges through warm shades of orange and yellow, standing in bold contrast against the vivid green matrix beneath them. That green coloration is due to a natural coating of celadonite, a mica-group mineral, together with traces of copper-bearing secondary minerals such as malachite, which are commonly found accompanying calcite formations in this region.

Geologically, specimens like this one formed within cavities of ancient basaltic lava flows that blanketed the region roughly 130 million years ago. As the molten rock advanced over older, water-saturated sandstone layers, superheated steam mobilized silica and calcium carbonate, which slowly crystallized inside gas pockets within the cooling basalt — the same geological process responsible for the famous amethyst geodes of this part of Brazil.

The specimen is reported by the seller to be completely free of damage, with every crystal intact and well formed. Its considerable size, the density and perfection of its crystal cluster, and its dramatic bicolor contrast make it a rare, high-impact piece suited both for a serious systematic mineral collection and for display as a striking natural sculpture.

Calcite is one of the most widespread carbonate minerals on Earth, composed of calcium carbonate (CaCO₃). In this specimen, the crystals display the classic elongated scalenohedral habit for which Iraí calcite is well known, with sharply defined, lustrous faces arranged in a dense radial pattern that gives the whole cluster its distinctive flower-like appearance.

The warm orange-to-yellow coloration of the calcite is commonly attributed to trace inclusions of iron oxide within the crystal lattice, a frequent coloring agent in carbonate minerals from volcanic host rocks. The vivid green tone of the underlying matrix, by contrast, comes from a natural coating of celadonite, a potassium- and iron-rich mica-group silicate, occasionally accompanied by traces of copper minerals such as malachite that are also known from this locality.

Calcite from Iraí is frequently reported to fluoresce under ultraviolet light, most commonly in shades of orange or pink under short and mid-wave UV. While this specimen is described as showing an intense yellow glow under UV exposure, fluorescence response can vary somewhat between individual specimens and UV wavelengths, so we recommend verifying the exact color response with a UV lamp upon receipt.

• Formula: CaCO₃ (Calcium Carbonate)
• Key chemical elements: Calcium (Ca), Carbon (C), Oxygen (O)
• Hardness (Mohs scale): 3
• Mineral class: Carbonates
• Crystal system: Trigonal
• Crystal habit: Scalenohedral, radiating flower-like cluster
• Formation: Hydrothermal precipitation within basalt geode cavities
• Color: Orange to yellow calcite on a green celadonite matrix
• Fluorescence: UV-reactive, reported intense yellow glow (verification recommended)

Iraí, in Rio Grande do Sul, sits within one of the most productive basalt geode fields in the world, an area more widely famous for its commercial-scale amethyst production than for calcite. Despite this, the calcite specimens that emerge from these same basalt cavities are considered among the most distinctive on the international market, prized for their crystal perfection and unusual radiating, flower-like clusters.

The geodes hosting these crystals began forming roughly 130 million years ago, when vast basaltic lava flows spread across the region and buried older, water-bearing sandstone layers. Superheated steam generated at the contact between the hot lava and underground artesian water mobilized dissolved silica and calcium carbonate, which slowly crystallized within gas pockets as the rock cooled — the same process that later produced the region's famous amethyst.

The vivid green color often seen coating Iraí calcite specimens comes from celadonite, a mica-group mineral that frequently lines the basalt cavities alongside the calcite, sometimes together with small amounts of copper minerals like malachite.

In crystal healing traditions, calcite is regarded as a gentle amplifier of energy, believed to cleanse and recharge the aura while encouraging clarity of thought and emotional balance. Orange and yellow calcite, in particular, are associated with vitality, creativity, and confidence, said to stimulate motivation and a positive outlook on life. The lush green tones of the celadonite matrix are sometimes linked to themes of grounding, renewal, and connection with nature, complementing the uplifting qualities attributed to the calcite itself. Some practitioners also value flower-shaped mineral clusters as symbols of growth and abundance, believed to radiate harmonious energy outward through the home or workspace. As with all metaphysical attributions, these interpretations are not scientifically proven.

Photos: All photographs are taken under professional lighting conditions to accurately highlight crystal structure, color and detail. However, slight variations in tone and appearance may occur depending on screen calibration and ambient lighting conditions.

Shipping: is handled through selected reliable express couriers, with fast delivery (often 1–2 business days within Europe), full tracking, insurance coverage and professional protective packaging, as confirmed by customer feedback and reviews.

Multiple purchases can be consolidated into a single shipment, including items from different auctions or separate orders, by simply contacting us to arrange combined shipping. For high-value specimens, direct delivery by appointment is also available, either at home or at major European mineral shows and fairs.