Final answer:
The most common type of meteorite to strike Earth is a rocky or stony meteorite, composed of light-colored silicates and metallic grains, dating back to 4.5 billion years ago. While iron meteorites are distinct for containing metallic iron, they are not as common as stony meteorites.
Step-by-step explanation:
The most common type of meteorite to strike Earth is rocky or stony. Meteorites that reach Earth have traditionally been classified into three broad classes: irons, stony-irons, and stones. Iron meteorites are composed of nearly pure metallic nickel-iron, while stony-irons are a mixture of stone and metallic iron. However, the great majority of meteorites that fall to Earth are primitive stones. These are often composed of light-colored gray silicates and sometimes include metallic grains. They are dated to the origin of the solar system, about 4.5 billion years ago.
Though iron meteorites, due to their metallic content, are the most obviously extraterrestrial, they are not the most common. Pure iron is extremely rare naturally on Earth as it is usually found as an oxide or other mineral ores. If you find a piece of metallic iron, it is likely man-made or a meteorite. However, primitive stones are much more common as meteorite falls because they are composed of materials that can be confused with terrestrial rocks until closely inspected.
The carbonaceous meteorites, another type of stony meteorite, contain carbon and complex organic molecules. Although these are scientifically significant for containing the building blocks of life and being from the outer asteroid belt, they are not the most common type of meteorite to hit Earth.