Sea Urchin Spine — Calcite Crystal Architecture at 5:1
319.00 د.إ
A sea urchin spine photographed at 5:1 macro — the calcium carbonate spine’s single-crystal structure revealed by its optical properties, the cross-sectional taper from the spine tip to the articulation base, and the surface micro-texture.
Description
Sea urchin spines are architectural marvels of biomineralisation — each spine is a single crystal of magnesium-containing calcite with a complex internal mesh structure (stereom) that provides mechanical performance equivalent to a composite material despite being a single crystalline phase. At 5:1 macro reproduction, the spine’s external geometry is fully resolved: the gradual taper from the blunt base articulation point to the sharp distal tip, the longitudinal striations on the surface that follow the crystal’s c-axis orientation, and the micro-texture of the calcite surface that reflects light with the characteristic birefringent glow of crystalline calcium carbonate. This image was made using a single oblique sidelight to emphasise the surface texture and the three-dimensional relief of the longitudinal striations. The translucency of the calcite crystal — visible at the spine’s tip where the cross-section is thin enough for light transmission — reveals the internal mesh structure as a subtle internal texture.
