Opal
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Opal is a hydrated amorphous form of silica ; its water content may range from 3% to 21% by weight, but is usually between 6% and 10%. Due to the amorphous physical structure, it is classified as a mi
A rich seam of iridescent opal encased in matrix
Main opal producing countries
Precious opal consists of a regular arrangement of silica nanospheres in closely packed planes (idealized diagram).
This precious rough opal from Coober Pedy, South Australia, displays nearly every color of the visible spectrum.
Silicon dioxide
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Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO2, and is commonly found in nature as quartz. In many parts of the world, silica is the major constituent of
Manufactured fumed silica with maximum surface area of 380 m2/g
Bundle of optical fibres composed of high purity silica
Quartz sand (silica) as main raw material for commercial glass production