Goethite after Siderite with Quartz

specimen number:
2341425

location:
Gourrama, Er Rachidia, Meknes-Tafilalet, Morocco

description:
Non-lustrous sharp brown opaque rhombohedral crystals of siderite, these replaced by goethite, measuring to 3.0 cm in size arrange nicely up on a matrix of gemmy crystals of quartz, these measuring to 3.0 cm in height. In good condition. The specimen comes with a previous label from the collection of Jan Erik Larsen.

The Gourrama area, located in the High Atlas regional transition zone near Er Rachidia, Morocco, features localized hydrothermal vein deposits hosted within Mesozoic sedimentary rocks. Artisanal mining and quarrying operations in the region have historically targeted iron and baryte occurrences, working small regional shafts and surface pits to extract ore minerals. For mineral collectors, Gourrama has gained distinction as a notable source of well-crystallized siderite specimens. Hydrothermal fluids precipitating iron carbonate in rock cavities generated sharp rhombohedral crystals and disk-like clusters of siderite, often showing translucent brown tones, and many specimens are naturally altered to dark goethite pseudomorphs after siderite. Local miners extract these crystals primarily by hand for the global specimen market, making Gourrama a recognized Moroccan locality for fine iron-carbonate mineral groups.

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