the manufacturing process for soda–lime glass consists in melting the raw materials, which are the silica, soda, lime (in the form of (ca(oh)), dolomite (camg(co), which provides the magnesium oxide), and aluminium oxide; along with small quantities of fining agents (e.g., sodium sulfate (naso), sodium chloride (nacl), etc.) in a glass furnace at temperatures locally up to 1675 °c. the temperature is only limited by the quality of the furnace structure material and by the glass composition. relatively inexpensive minerals such as trona, sand, and feldspar are usually used instead of pure chemicals. green and brown bottles are obtained from raw materials containing iron oxide. the mix of raw materials is termed batch.