Chert

{
  "id": "MLC-T-OAG-000655",
  "term": "Chert",
  "field": "Oil and gas",
  "definition": "A hard, dense, cryptocrystalline sedimentary rock composed of microcrystalline quartz (silica). It forms either by direct precipitation from silica-rich waters or by the diagenetic replacement of other minerals, such as carbonates. Chert can occur as nodules within limestone or as bedded deposits, and its presence can complicate drilling operations due to its hardness.",
  "subject": "Geology",
  "url": "https://mlchart.com/terminology/oil-and-gas/chert/"
}