Quartz
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An impressive large attractive matrix plate covered with royal purple glassy gemmy crystals of amethyst. This is an antique example collected in the 19th century. Damage is present, but the color is outstanding. The specimen comes with an old label as shown at at one time the piece was part of the collection of Wilhelm Hoyer.Amethyst from Rio Grande do Sul, Brazil, occurs within the vast Serra Geral Formation, a major volcanic province formed during the Early Cretaceous period. Geologically, the amethyst deposits developed when silica-rich hydrothermal solutions filled gas cavities, known as vesicles, within extensive basalt lava flows, resulting in the creation of massive volcanic geodes lined with purple quartz crystals. Historically, commercial extraction and lapidary work in the region began to flourish in the late 19th and early 20th centuries, largely driven by European immigrants settling in areas like Ametista do Sul, transforming the district into one of the world's largest and most prolific suppliers of commercial amethyst geodes.
Product details
SpeciesQuartz
SizeMuseum
Dimensions32.0 x 26.0 x 8.5 cm
Listed on08/25/2026
LocalityBrazil, Rio Grande do Sul
SKU1052895
Current owner
WM
Weinrich MineralsFeatured
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Mineral guide
Learn about Quartz
a versatile mineral with clear, milky, and colored varieties; crystal forms, formation clues, and tips for identifying amethyst and citrine.Regional guide
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