ʻO ka hui kemika o nā peʻa lana ka nui o ka silicon dioxide a me ka alumini oxide.He nui nā hiʻohiʻona e like me nā ʻāpana maikaʻi, hollow, ke kaumaha māmā, ka ikaika kiʻekiʻe, ke kūpaʻa ʻana, ke kūpaʻa wela kiʻekiʻe, ka insulation thermal a me ka pale ahi.Hoʻohana nui ʻia ia i kekahi o nā mea maka no ka ʻoihana refractory.