Quartz

specimen number:
2072366

location:
Mamaju, West Sulawesi, Indonesia

description:
Purple semi lustrous botryoidal crystallized quartz coming off matrix. In good condition all around.

The Mamuju area, located on the island of Sulawesi, Indonesia, is the premier locality for the unique botryoidal mineral specimens marketed globally as "grape agate." Geologically, this material is not a true chalcedony or agate, but rather a form of crystallized amethystine quartz that precipitated from hydrothermal fluids into cavities within volcanic andesite and basalt. The distinctive purple to lavender spheres are composed of radiating micro-crystals of quartz that have formed a botryoidal or "bunch of grapes" habit. Historically, while local mining for various stones has existed for some time, the systematic extraction of these purple quartz specimens for the international market began around 2015 and 2016. The mining and quarrying operations are primarily artisanal, involving local villagers who dig into the weathered volcanic rock to recover the fragile clusters from muddy seams and pockets. As of 2026, Mamuju remains the only significant source for this specific variety of botryoidal quartz, which is highly valued by collectors for its vivid color and unusual globular morphology.

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