Andradite

specimen number:
2262333

location:
Kayes region, Mali

description:
A grouping of lustrous black andradite crystals with little attached matrix. In good condition as seen.

The Kayes region in western Mali, specifically near the town of Diakon, is globally renowned for its unique modern production of high-quality garnets, primarily consisting of the andradite and grossular varieties. Geologically, these rich deposits are hosted within extensive contact-metamorphic skarn zones that formed during the Paleoproterozoic era, where major Neoproterozoic-age dolerite sills and dikes intruded ancient, calcareous sedimentary rocks of the Taoudeni Basin. This intense contact metamorphism recrystallized the impure limestones and marbles, introducing silica and iron-rich hydrothermal fluids that generated distinct skarn assemblages containing epidote, quartz, calcite, and massive clusters of andradite garnet (including the rare, yellowish-green to olive-green variety known as demantoid). Historically, while localized panning and shallow digging for gold and miscellaneous minerals had occurred across the region for centuries, the specific discovery of these high-grade andradite-grossular garnet zones occurred relatively recently, with formal exploratory pitting and artisanal surface quarrying commencing in 1994. The area quickly triggered a major mineral-rush, with corporate consortiums and thousands of independent local miners establishing highly active open-cast quarries and shallow underground pits to extract the garnets for international markets. Large-scale corporate mining and mechanized sorting facilities peaked in production during the late 1990s and early 2000s, and while organized corporate operations contracted significantly due to political changes and fluctuating market demands, localized artisanal open-cut mining and mineral-specimen extraction continue to actively operate in the Kayes region through 2026.

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