Borosilicate glass

Borosilicate glass, also called borosilicate glass, consists of about 80% SiO2 ("silicate") and about 10% B2O3 ("boron" trioxide), and another 10% or so of other minerals (Al2O3, K2O, CaO, MgO). Borosilicate has a very high chemical and thermal resistance. Borosilicate is used for vacuum chambers and windows of plasma chambers which need to be resistant to etching attacks.