What type of reaction is #SiO_2 + HF -> SiF_4 + H_2O#?
An acid-base reaction, where hydrogen fluoride is the acid, and the base is glass.
One of the major uses of hydrogen fluoride (or hydrofluoric acid) is to etch glass, so this reaction is directly exploited. Hydrofluoric acid is treated with great respect (i.e. with meticulous care) in the laboratory.