Refractories are materials having high melting points, with properties that make them suitable to act as heat resisting barriers between high and low-temperature zones. Refractories are useful in constructing application-specific high-temperature areas/surfaces, particularly in furnaces or boilers, as they minimize heat losses through the structure. The value of refractories is judged not merely by the cost of the material itself, but by the nature of a job and/or its performance in a particular situation. Specifically, the performance of a refractory depends on its qualities and quantities in three phases—solid, gas/liquid, and pores—which govern the ultimate property of refractory material.