There would be no bright and colorful fireworks without ... calcium is very common in limestone rocks composed of calcite and dolomite. A single calcite crystal. Burning magnesium, titanium ...

In this case, the material is microscopic crystals ... obsidian appear colorful, rather than the mineral itself. As with other forms of obsidian, rainbow obsidian is both rock and glass.

This reliquary holds a bone fragment purportedly belonging to Saint Sebastian, within a central rock-crystal vessel ... decorated above and below the bone fragment with a plethora of colorful gems ...