Quartz

specimen number:
2072135

location:
Mamaju, Sulawesi, Indonesia

description:
A loose floater cluster of lustrous purple botryoidal crystallized quartz. No points of attachment and complete all around. Minimal damage present.

The Mamuju region, located in West Sulawesi, Indonesia, is situated within a complex geological setting characterized by Tertiary-aged volcanic and plutonic rocks of the Western Sulawesi Volcano-Plutonic Belt. The quartz deposits in this area typically occur as hydrothermal vein fillings within altered volcanic rocks, specifically dacites and andesites that have undergone extensive fracturing. Historically, the area gained international attention in the early 21st century as a source of unique, high-quality quartz specimens, most notably the "grape agate" which is actually a botryoidal form of amethystine quartz. While amethyst is a primary focus, the region also produces sharp, colorless to smoky quartz crystals that often display a distinctive "artichoke" or "sprossen" growth habit, reflecting the fluctuating temperatures and pressures within the hydrothermal systems during the final stages of the island's tectonic assembly.

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