Blue frit, also known as Egyptian blue, was made from quartz, lime, a copper compound, and an alkali flux, all heated to a temperature between 850 and 1000 °C. Quartz sand may have been used to contribute silica to the frit. The copper content must be greater than the lime content in order to create a "blue" frit. Ultimately the frit consists of cuprorivaite (CaCuSi4O10) crystals and “partially reacted quartz particles bonded together” by interstitial glass. Despite an argument to the contrary, scientists have found that, regardless of alkali content, the cuprorivaite crystals develop by “nucleation or growth within a liquid or glass phase.” However, alkali content—and the coarseness of the cuprorivaite crystals—contribute to the shade of blue in the frit. High alkali content will yield “a large proportion of glass,” thereby diluting the cuprorivaite crystals and producing lighter shades of blue. Regrinding and resintering the frit will create finer cuprorivaite crystals, also producing lighter shades.