Corundum requires what type of environment to form?

Corundum, which includes gemstones like sapphires and rubies, typically forms in environments that are low in silicon. This is significant because corundum is an aluminum oxide mineral, and its formation is heavily influenced by the availability of aluminum and oxygen over silicon. While some other minerals, like quartz, are silicon-rich and form in environments abundant in silica, corundum thrives in conditions where silicon is minimal, allowing the aluminum and other trace elements to crystallize and form the distinct structures characteristic of corundum.

In geological terms, corundum usually forms in metamorphic rocks or in igneous rocks that are low in silica, such as certain types of basalt. The presence of aluminum sources in these settings contributes to the conditions that favor the crystallization of corundum. Understanding this process is essential for recognizing how different gemstones are formed and the environments that contribute to their unique features.