niecakowite

Niecakowite is a term used in geology and paleontology to describe substances, sediments, or fossils that contain little or no calcium carbonate (CaCO3). The word denotes the opposite of calcareous materials, which are rich in carbonate minerals such as limestone or shells largely composed of calcite or aragonite. In practice, niecakowite materials are typically non-calcareous or carbonate-poor.

In sedimentology, niecakowite sediments include quartz-rich sandstones, siltstones, claystones, and other siliciclastic or non-carbonate deposits. They contrast with calcareous sediments like limestones and dolostones. The carbonate content is often determined by geochemical analyses and by simple field tests; many niecakowite rocks do not effervesce with dilute hydrochloric acid, whereas calcareous rocks readily fizz due to carbonate dissolution.

Niecakowite deposition commonly occurs in environments where carbonate supplies are limited or where physical rather than chemical processes prevail, such as some deep-water, arid, or clastic-dominated settings. The absence of calcium carbonate affects diagenetic pathways, fossil preservation, and the potential for certain resource developments, including reservoir quality in sedimentary basins.

In paleontology, the term can describe fossils or skeletal materials that are not calcareous, including those with non-calcareous tissues or with skeletons that have been replaced or preserved by non-carbonate minerals. The concept helps distinguish preservation and taphonomic processes that differ from those of calcareous remains.

Niecakowite is most commonly encountered in Polish-language geology and paleontology literature and is used to categorize carbonate-poor materials within broader sedimentological classifications.