Quartz

specimen number:
2072319

location:
Rio Grande do Sul, Brazil

description:
An attractive large matrix plate with glassy gemmy purple crystals of quartz to 2.0 cm in size. Minimal damage present, still in good condition. This is the variety of the species known as amethyst.

The amethyst deposits of Rio Grande do Sul, Brazil, are primarily centered around the city of Ametista do Sul and are situated within the massive Parana Continental Flood Basalt Province. Geologically, these world-class deposits occur in the form of enormous geode-bearing basalt flows, where gas bubbles trapped in cooling lava approximately 130 million years ago were later filled by silica-rich hydrothermal fluids that crystallized into vibrant purple amethyst. Historically, the discovery of these gemstones dates back to the early 19th century, with significant commercial mining and quarrying activities gaining momentum in the 1970s as agricultural workers transitioned into gemstone extraction. Unlike traditional deep-vein mining, these operations typically involve horizontal tunnels or "galerias" driven directly into the basalt hillsides to carefully extract the intact geodes. As of 2026, the region remains the most prolific producer of amethyst in the world, supporting an extensive industrial infrastructure dedicated to the mining, processing, and global export of these volcanic treasures.

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