A fascinating natural Moroccan pseudo-stromatolite sand concretion, weighing approximately 159g.
Commonly known within the mineral and fossil trade as a “Sand Stromatolite” or “Desert Onion”, these unusual Saharan formations are more accurately regarded as natural mineral and sandstone concretions rather than true fossil stromatolites.
This especially attractive specimen consists of two naturally joined rounded formations, each displaying concentric ring structures across its exposed face. The larger formation has a particularly well-defined central nucleus surrounded by successive circular layers, creating a striking bullseye-like appearance.
Viewed from different angles, the specimen changes dramatically from a pair of rounded sandy nodules to a sculptural double formation with the internal concentric structures clearly exposed.
Warm sandy orange, terracotta and cream tones run throughout the naturally granular surface.
Details:
Moroccan pseudo-stromatolite / sand concretion
Common trade name: Sand Stromatolite / Desert Onion
Natural double-node formation
Two exposed concentric structures
Natural, unpolished specimen
Sahara Desert, Morocco
Weight: approximately 159g
Exact specimen shown in the photographs
As this is a completely natural geological formation, irregular surfaces, minor fissures, loose grains and natural weathering are to be expected and form part of its character.