A striking split and polished ammonite pair from Indonesia, revealing a beautifully preserved spiral of mineral-filled internal chambers, with an additional surprise under ultraviolet light.
In ordinary light, the polished faces display pale crystalline chambers outlined by warm golden-brown septa, creating an exceptionally clear spiral pattern from the center of the shell outward. Several chambers contain small open crystal pockets, adding natural texture and sparkle among the larger mineral-filled sections.
Under UV light, the specimen transforms dramatically. Both halves exhibit red and yellow fluorescence, with individual chambers lighting up against the darker surrounding material. After the UV source is removed, the specimen also displays red and green phosphorescence, producing a brief visible afterglow. Please see the listing video for the phosphorescent response.
The mineralization responsible for these effects developed during fossilization as the original shell and its chambers were altered and filled by minerals over geologic time. UV-reactive calcite-filled ammonites are known from Indonesia, with some specimens exhibiting both fluorescence and phosphorescence.
This is a naturally imperfect fossil pair. The two halves are not identical in outline, and portions of the outer whorl are incomplete or broken. Unlike some heavily prepared Indonesian ammonites, the exterior has also been left largely in its natural fossil matrix rather than being carved down to emphasize the spiral. These characteristics are visible in the photographs and are reflected in the price.
Ammonites were extinct marine cephalopods related to modern squid, octopuses, and cuttlefish. Their chambered, coiled shells are among the most recognizable forms in the fossil record.
Details Specimen: Ammonite Locality: Indonesia Size: Approximately 3.3" × 2.9" Weight: Approximately 337 g total (188 g + 149 g) Two polished halves of a single ammonite Mineral and crystal-filled internal chambers Small natural crystal pockets Fluorescent under UV: red and yellow Phosphorescent after UV exposure: red and green (see video) Natural incomplete/broken areas present One-of-a-kind fossil specimen
You will receive the exact ammonite pair pictured.