Cristobalite

Cristobalite is a high-temperature polymorph of silica (silicon dioxide, SiO2), existing in a tetrahedral crystal structure. It forms at temperatures above approximately 1470°C (2680°F) and then transforms into a tetragonal structure at around 260°C (500°F). This transformation is associated with a significant volume change, making cristobalite a crucial factor in the durability of ceramic materials and concrete. Its presence, or the phase transformation between the two crystal structures, influences thermal shock resistance and is crucial in certain industrial processes such as the manufacture of refractory materials. cristobalite is a relatively rare mineral found in volcanic rocks and, rarely, in meteorites.

Cristobalite meaning with examples

• The sudden cooling of the volcanic lava, a process known as rapid quenching, can cause the formation of cristobalite, embedding within the glassy matrix. Scientists study these formations to help to determine the speed of the lava. It's an important indicator, alongside other minerals in the volcanic composition and can help determine the composition of the geological event.
• During high-temperature firing of ceramic tiles, the formation of cristobalite is carefully controlled to achieve the desired properties. Manufacturers must find the perfect temperatures to ensure the tile does not crack during the cooling phase, as the volume changes can lead to cracks. It's critical for structural integrity.
• The presence of cristobalite in concrete can lead to expansion and cracking over time, especially with repeated thermal cycling. Modern concrete formulations often try to limit cristobalite formation to improve durability and resistance to this degradation. This is extremely important for the longevity of bridges.
• Refractory bricks used in high-temperature furnaces are often designed to incorporate cristobalite to increase their thermal shock resistance. The crystal structure provides excellent resistance to thermal shock as the heat rises and falls. This critical design aspect helps the furnace stand the test of time.
• Geologists use cristobalite as an indicator mineral to reconstruct the thermal history of certain rock formations. The specific temperature range of transformation can help indicate past heating events. This data can help us interpret the rock’s history and understand past geological activity.