Ceramics: Clay

Clay: a type of fine-grained natural soil material that contains hydrous aluminium phyllosilicates (clay minerals) that develops plasticity when wet.
Silicate: any member of a family of anions consisting of silicon and oxygen
* The family includes orthosilicate, metasilicate and pyrosilicate.
Phyllosilicates: sheet silicate minerals, formed by parallel sheets of silicate tetrahedra with Si2O5 or a 2:5 ratio.

100C-125C: Residual (unbound) water; kaolin is transformed into metakaolin
200C-1000C: Organic material burns off
350C-525C: Lattice water (water a part of the crystalline structure) is removed; no shrinkage occurs
573C: Low quartz is transformed into high quartz
790C: Magnesium carbonate decomposes to magnesium oxide and carbon dioxide
870C: Quartz is transformed into tridymite
880C: Calcium carbonate decomposes to calcium oxide and carbon dioxide
950C: Metakaolin is transformed into a defect, spinel-type structure
1000C-1250C: Mullite is formed from the feldspar present
1100C-1300C: Calcium sulfate and magnesium sulfate decompose
1470C: Tridymite is transformed into cristobalite
All these transitions are very slow processes
The volume change (shrinkage): 10 – 15 %
Ceramic: combination of one or more metals or semimetals (silicon) with oxygen, linked by ionic and covalent bonds into a polymeric matrix.
Types of ceramic pottery: earthenware, stoneware, bone china, porcelain and vitrified pottery.
Fired ceramic objects are porous; this is why they are coated with a glaze (properties identical to glasses). It make pottery non-porous and watertight, it improves the strength of the object and it adds additional visual effect.