For some animals, developing hard shells of silica , or incorporating calcium in bones and teeth, has clear benefits.
The silicate minerals are those that contain silica , a combination of silicon and oxygen.
Quartz and sand are composed of silicon and oxygen alone: silicon dioxide, or silica .
In the fossilisation process, the original organic parts of the shark's tooth are replaced by minerals such as iron pyrites and silica .
Soils are generally clay silica of varied depths and exposures.
Precipitation of gold is favoured by similar conditions to those that favour precipitation of silica .
Soluble silicates can be obtained by heating alkali metal carbonates and silica .
Cristobalite is a crystalline form of silica that has a diamondlike structure.
Sandy soil attached to the furs was the source of silica in the fur dust.
Glass is made from silica the most common mineral on the planet and aluminium is the most abundant metal on earth.