What is Silica?

About Silica:

• Silica is another name for the chemical compound composed of two most abundant elements in Earth’s crust, silicon and oxygen, SiO2.
• The mass of Earth’s crust is 59 percent silica, the main constituent of more than 95 percent of the known rocks.
• Silica exists in many different forms that can be crystalline as well as non-crystalline (amorphous).
• Silica has three main crystalline varieties: quartz (by far the most abundant), tridymite, and cristobalite. 
• Other varieties include coesite, keatite, and lechatelierite. 
• Uses:
  • Silica sand is used in buildings and roads in the form of port land cement, concrete, and mortar, as well as sandstone.
  • Silica is also used in grinding and polishing glass and stone; in foundry molds; in the manufacture of glass, ceramics, silicon carbide, ferrosilicon, and silicones; as a refractory material; and as gemstones.
  • Silica gel is often used as a desiccant to remove moisture.

Q1: What is tridymite?

Tridymite is a low pressure, mostly high-temperature-stable polymorph of silica that can also form or persist metastably at low temperatures. 

News: Silica mining: NGT asks CPCB to prepare pan-India guidelines

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