A silicate is a kind of solid mineral, very common in the earth. Think of it as a family of rocks and crystals whose chemistry is built around silicon and oxygen, often with metals mixed in. Most of the stone under your feet is silicate of one sort or another — granite, mica, clay, even the glassy skin of some lava. Geologists and chemists use the word; ordinary talk just says “rock” or “clay.” Though actually, “silicate” is not one mineral. It is a whole group, the way “salt” in chemistry is a whole group, not only table salt. People also say “silicate” in industry for compounds used in glass, cement, and detergents. The everyday object is still the earthy one: the ground itself is largely silicates.