Fireplace Mortar is a silicate-based refractory cement caulk ideal for tuck-pointing damaged firebox mortar joints, chips, cracks, and spalls commonly found in fireplaces and wood-burning stoves. Once cured, the mortar provides superior adhesion for a durable repair while withstanding heats up to 2000° F. It is sold in 10 oz. tubes. Quikrete Cos.