AMETHYST WITH CALCITE

ABOUT THE SPECIMEN

Ametista do Sul is, true to its name, recognized as the amethyst-producing capital of the world. Here we have deep purple amethyst crystals, displaying an unusually rich saturation reminiscent of Uruguayan material, forming a complete carpet across the specimen's face. These are dramatically accented by exceptional calcite crystals reaching 12 cm, their gem-like transparency creating a striking contrast against the amethyst backdrop. While specimens from this prolific region are well-known, this particular piece stands several cuts above the norm, possessing the size and aesthetics to command center stage in any serious mineral display.

MORE INFO

The mineralization sequence in Ametista do Sul's basalt cavities proceeds in distinct stages. Initial hydrothermal fluids deposit celadonite, followed by primary quartz crystallization. Subsequent radiation-induced oxidation of iron within the quartz structure produces amethyst. The final phase introduces calcium-rich solutions, resulting in scalenohedral calcite precipitation on amethyst surfaces. This low-temperature hydrothermal process (<100°C) occurs within vesicles in the host basalt, forming geodes that frequently exceed two meters in diameter.