1) Calcium mineral 
Jennite is a calcium silicate hydrate mineral of general chemical formula: Ca9Si6O18(OH)6·8H2O. Jennite occurs as an alteration mineral in metamorphosed limestone and skarn. It typically occurs as vein and open space fillings as a late mineral phase. It also occurs in hydrated cement paste. A first specimen of jennite found in 1966 at the Crestmo...