Gilalite is a copper with chemical composition of Cu5Si6O17·7(H2O).
It occurs as a retrograde metamorphic phase in a calc-silicate and sulfide skarn deposit. It occurs as fracture fillings and incrustations associated with diopside It is commonly found in the form of spherules of radial fibers.
It was first described for an occurrence in the Christmas porphyry copper in 1980 along with the mineral apachite It derives its name from this locality. It has also been reported from the Goodsprings District, Clark County, Nevada; Juazeiro do Norte and a slag area in Lavrion District , Greece