Silicon is the eighth most abundant element in the universe. Silicon dioxide (or silica) is present in over 90% of the minerals that make up the earth’s crust. Man’s use of silica-based minerals dates back to the very origins of recorded human history. Ancient man used flint to strike sparks for the fires they needed to stay warm, while today modern man can be protected from heat of reentry into the Earth’s atmosphere thanks to silica-based tiles that protect the space shuttle.
In paints and coatings, siliceous minerals were known to have been used as pigments in the oldest surviving cave paintings dating back to 40,000 BC. Naturally occurring forms of silica and silicate are still used today as functional fillers, with the silicon atoms determining much of the overall character of these minerals. Silica forms tetrahedral arrangements. The tendency of these units to form a three-dimensional framework is fundamental to silica crystal chemistry, which in turn directs the arrangement of the minerals’ structure into the lattice shapes that determine their particle shape and other characteristics.1,2