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Building Blocks: What is the Difference Between Rocks and Minerals?

based on 3 ratings
Author: Janice VanCleave

Problem

What is the difference between rocks and minerals?

Materials

  • 3 toothpicks
  • 6 red gumdrops (or any dark color, such as green or black)
  • 3 white gumdrops (or any light color, such as pink or yellow)
  • Marking pen
  • 3 resealable plastic bags

Procedure

  1. Insert 1 toothpick each in 3 of the red gumdrops.
  2. Place a white gumdrop on the other end of each toothpick.
  3. Label the plastic bags Mineral 1, Mineral 2, and Rock.
  4. Place 2 of the remaining red gumdrops in the bag labeled Mineral 1, and 2 of the red-and-white gumdrop sets in the bag labeled Mineral 2. In the bag labeled Rock, place the last red gumdrop and the third red-and-white gumdrop set.

Results

You have made models of two different minerals and one rock.

Why?

Rocks and minerals have two things in common. First, like all materials in the universe, they are matter. Matter is anything that has mass (an amount of material) and takes up space. The building units of matter are called atoms. If matter is made of only one kind of atom, it is called an element. When two or more elements are combined, the combination of elements is called a chemical compound. The smallest part of a chemical compound that retains the properties of the compound is called a molecule. Molecules consist of atoms held together by chemical bonds. Second, rocks and minerals are solids (phase of matter with a definite shape and a definite volume).

In the experiment, the red gumdrops represent atoms of the same element, called element 1, and the white gumdrops represent atoms of a second element called element 2. The red-and-white gumdrop sets represent molecules of a chemical compound formed by the combination of atoms of element 1 and element 2. The toothpicks represent the chemical bonds that hold atoms of the two elements together.

A mineral is a single solid element or chemical compound found in the earth and that has four basic characteristics. First, a mineral occurs naturally. Rubies formed in the earth are minerals, while man-made rubies are not. Second, a mineral is inorganic (not formed from the remains of living organisms). Diamonds are formed from pure carbon inside the earth, but coal is formed from carbon that was once part of living things. Thus, diamonds are minerals, while coal is not. Third, each kind of mineral has a definite chemical composition, meaning the amount and kind of matter are the same for a given mineral. Fourth, each mineral has a definite structure known as a crystal (a solid made up of atoms arranged in an orderly, regular pattern). Perfect crystals have flat sides. Table salt is a mineral with crystals shaped like tiny cubes. The bag labeled Mineral 1 is a model of a mineral made up of element I atoms only. Mineral 2 is a model of a mineral made of molecules of atoms of elements 1 and 2.

Building Blocks

Rocks are solids made up of one or more minerals, but they are not restricted to all four characteristics that describe minerals. The difference between rocks and minerals can be compared to the difference between model airplanes and the materials used to build them. Just as the building blocks of rocks are minerals, the building blocks of model airplanes are wheels, wings, propellers, and other parts. The main identifying characteristic of rocks is that they are mixtures. The model of the rock in this experiment is a mixture of an element and a chemical compound. Some rocks are granite, marble, and lava.

Rocks and minerals are the building blocks of the earth's lithosphere. The lithosphere includes all of the earth's crust (the relatively thin outermost layer of the earth) and the upper part of the earth's inner layer called the mantle. The lithosphere extends to a depth of about 63 miles (100 km). Thousands of different minerals have been identified in the earth's lithosphere. Only about 12 minerals are abundant and are called rock formers because they make up the bulk of the lithosphere.

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