Calcite w/ Marcasite after Thalassinoides

Linwood Mine, Buffalo,

Scott Co., Iowa

USA

9x2x4.5cm

Exceptional calcite specimen featuring marcasite pseudomorphs after thalassinoides burrow structures. This rare Iowa piece showcases the interplay between mineral replacement and paleontological form—the marcasite has replaced the original burrow infill, creating striking metallic luster against translucent calcite matrix. From the historic Linwood Mine in Scott County, a locality prized by collectors for its distinctive mineral associations and well-preserved specimens. The specimen measures 9 × 2 × 4.5 cm and displays excellent contrast and definition. A compelling addition to collections focused on Iowa minerals, pseudomorphs, or paleontological-mineralogical intersections.