Identifying faience
Glazed quartz, not clay.
Egyptian faience is a glazed non-clay body of ground quartz, usually blue-green from copper. The core is pale and granular where chipped — a sugary fracture quite unlike the dense red or brown body of glazed pottery.
Amulets, beads, shabtis, and small vessels are the common forms. The glaze is often self-formed (the glazing salts migrate to the surface as the piece dries), which is why colour can sit unevenly and pool in hollows.
Blue-green dominates, but later faience runs to white, yellow, and violet; faded surfaces can look almost colourless with the glaze surviving only in recesses.
Faience is porous and soluble salts are its enemy — keep it dry and never soak it. Record body colour at any chip, glaze colour, and form; those three usually place a piece.