Calcite with Celadonite

specimen number:
2292304

location:
Irai, Rio Grande do Sul, Brazil

description:
Colorless crystals of calcite measuring to almost 4.0 cm in size, these a light green in color due to celadonite. In good condition. Brightly fluorescent. This is classic material for this locality.

The Irai municipality, located in the northern volcanic zone of Rio Grande do Sul, Brazil, is a highly significant mineral locality famous for producing unique combinations of calcite nested within celestial-green celadonite coatings. Geologically, these minerals crystallized inside massive, hollow vesicular cavities embedded within the Lower Cretaceous basaltic flood basalts of the Parana Basin. During late-stage volcanic cooling, low-temperature hydrothermal fluids saturated with iron, magnesium, and potassium first lined the interior basalt cavity walls with a dull-to-vibrant green layer of the silicate mineral celadonite. Subsequent fluid pulses introduced calcium carbonate, precipitating sharp, translucent, colorless-to-white scalenohedral calcite crystal prisms directly on top of or enclosing the green celadonite matrix, resulting in a striking color contrast. Artisanal surface digging and quarrying for agates and geodes in the surrounding territory date back to the mid-nineteenth century, with subterranean shaft exploration and specialized geode mining around Irai accelerating in the 1960s and 1970s. While regional operations peaked during the late twentieth century to satisfy global collector demand, small-scale artisanal extraction from these specialized volcanic pockets continues intermittently today.

Questions about this specimen?
Send an email or call us: 314-341-1811.