<P> Calcium carbonate has traditionally been a major component of blackboard chalk . However, modern manufactured chalk is mostly gypsum, hydrated calcium sulfate CaSO 2H O. Calcium carbonate is a main source for growing Seacrete, or Biorock . Precipitated calcium carbonate (PCC), pre-dispersed in slurry form, is a common filler material for latex gloves with the aim of achieving maximum saving in material and production costs . </P> <P> Fine ground calcium carbonate (GCC) is an essential ingredient in the microporous film used in diapers and some building films as the pores are nucleated around the calcium carbonate particles during the manufacture of the film by biaxial stretching . GCC or PCC is used as a filler in paper because they are cheaper than wood fiber . In terms of market volume, GCC are the most important types of fillers currently used . Printing and writing paper can contain 10--20% calcium carbonate . In North America, calcium carbonate has begun to replace kaolin in the production of glossy paper . Europe has been practicing this as alkaline papermaking or acid - free papermaking for some decades . PCC used for paper filling and paper coatings is precipitated and prepared in a variety of shapes and sizes having characteristic narrow particle size distributions and equivalent spherical diameters of 0.4 to 3 micrometres . </P> <P> Calcium carbonate is widely used as an extender in paints, in particular matte emulsion paint where typically 30% by weight of the paint is either chalk or marble . It is also a popular filler in plastics . Some typical examples include around 15 to 20% loading of chalk in unplasticized polyvinyl chloride (uPVC) drain pipe, 5 to 15% loading of stearate coated chalk or marble in uPVC window profile . PVC cables can use calcium carbonate at loadings of up to 70 phr (parts per hundred parts of resin) to improve mechanical properties (tensile strength and elongation) and electrical properties (volume resistivity). Polypropylene compounds are often filled with calcium carbonate to increase rigidity, a requirement that becomes important at high use temperatures . Here the percentage is often 20--40% . It also routinely used as a filler in thermosetting resins (sheet and bulk molding compounds) and has also been mixed with ABS, and other ingredients, to form some types of compression molded "clay" poker chips . Precipitated calcium carbonate, made by dropping calcium oxide into water, is used by itself or with additives as a white paint, known as whitewashing . </P> <P> Calcium carbonate is added to a wide range of trade and do it yourself adhesives, sealants, and decorating fillers . Ceramic tile adhesives typically contain 70 to 80% limestone . Decorating crack fillers contain similar levels of marble or dolomite . It is also mixed with putty in setting stained glass windows, and as a resist to prevent glass from sticking to kiln shelves when firing glazes and paints at high temperature . </P>

How to find chemical formula of calcium carbonate