Today’s synthetic silicas are highly specialized materials that have become critical ingredients in toothpaste, rubber tires, plastics and coatings, with a combined global production estimated at 3.2 million metric tons for 2016. The synthetic routes produced materials with higher purity than the natural mineral varieties, and enabled chemical and morphological customizations that expanded the utility of silicas into new applications. 3 The first synthetic silicas began commercial production around the time of World War I. Jöns Jakob Berzelius is credited as being first to isolate silicon and characterize it as an element in 1824, which paved the way for a considerable history of advances in silicon-based chemistry. (It is important to note that synthetically produced materials are amorphous and typically do not contain crystalline phases of silica.) While many of the characteristics of the natural materials are ideal as fillers for coatings (low binder demand, inertness, etc.), crystalline silica has gained much recent attention based on health concerns and regulatory developments. The naturally occurring minerals typically contain some amount of crystalline silica, either as a minor component or as the principal component of their makeup. Naturally occurring siliceous mineral fillers include silicon dioxide in forms such as quartz and cristobalite, or silicate like mica, talc and kaolin. 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. ![]() 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. 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. 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. Man’s use of silica-based minerals dates back to the very origins of recorded human history. ![]() Silicon dioxide (or silica) is present in over 90% of the minerals that make up the earth’s crust. ![]() Silicon is the eighth most abundant element in the universe.
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