Schiller is caused by the reflection of light

Sedimentary rocks can take thousands to millions of years to form

Silicate minerals important class of rock-forming minerals

Oxygen and silicon make up about 75% of Earth's crust

Silicon dioxide occurs in nature as crystalline quartz

St Edward's sapphire in the Maltese Cross in the Imperial State Crown

Sterling silver often described incorrectly as solid silver

A streak test can be used to help identify certain minerals

Stromatolite from the Greek for 'layered rock'

The Stuart Sapphire mounted in the back of the Imperial State Crown

The Sweet Home Mine in Colorado famous for rhodochrosite