The size of crystals in a rock can reveal something about how the rock formed. Slow coo gives indiv crystals suffi time t grow bec particles c join exis ordered struc before t surrounding mate becomes solid. Molten rock insulated deep underground often loses heat gradually and develops crystals visible without a microscope. At the surface, rapid cooling commonly produces much smaller crystals. A rock containing large crystals surrounded by a finer material can record two stages: growth began slowly below ground, then continued more rapidly after the molten material moved upward.

Type only the missing letters. Each box is one letter, and the number of boxes matches the letters that are missing.