AMM271 Ammonite Fossil (South Dakota) Collector 4cm x 12cm polished face

4cm x 12cm polished face

and intense white banding with sections of intense parallax

so that the interesting formations in the Blue Opal can be seen

and are often referred to as “composite cabochons

33mm x 33mm

AMM271 Ammonite Fossil (South Dakota) Collector 4cm x 12cm polished faceThis ammonite specimen comes from South Dakota in the Cretaceous period when the area was submerged by the Western Interior Seaway millions of years ago. They are typically preserved in hard concretions that must be carefully removed. This sizeable fossil shows mixes of brown and yellow calcite with a smooth surface displaying complex leafy suture patterns. It has a fairly well preserved chamber opening and spots of red, yellow, and green iridescence.