商品の詳細

Ammonite Shell Fossilized. Specimen is completely polished, the back has the iridescent coloring known as ammolite which is often colors of green and red. The colors are not caused by pigments, but by light refracting through micro-thin layers of a mineral called aragonite. Dimensions: 1-1/8" long x 1-1/4" Tall x 1/2" Wide. Thank you for looking. Ammonite fossils form when a dead ammonite sinks to the seafloor, gets buried by sediment, and undergoes mineralization. As the organic shell is preserved or replaced by minerals like calcite, silica, or pyrite, the sediment hardens into rock. The step-by-step process: Burial: When an ammonite dies, its shell sinks to the ocean floor. The soft tissues are eaten or decay, leaving only the hard, spiral shell. Sedimentation: Thick layers of sand, silt, and mud quickly bury the shell, protecting it from scavengers and oxygen. Permineralization: Over millions of years, water containing dissolved minerals seeps through the sediment. As the original shell material slowly dissolves, minerals fill the empty internal chambers, acting as natural molds. Crystallization: The minerals harden inside the shell's hollow spaces, often forming beautiful quartz, calcite, or pyrite crystals. Exposure: Tectonic forces cause the seafloor to rise, turning it into dry land. Wind and rain erode the surrounding rock, leaving the durable fossil exposed.