Rocks of the USA - Hand-Sized Rock Collection

Encourage your little geologist with this 16 common rocks and minerals collection on a 4x6" inch card. Facts about the rocks and minerals are printed on the back of the card. Let your explorer unleash their inner geologist! With these 16 rocks and minerals, they can learn all about the earth and become the rock stars of their class. (They might find a few gems along the way, too.)

Is it a Mineral or a Rock?

To a casual observer, a rock and a mineral are alike. However, to a geologist, a rock is much different from a mineral!

A Mineral is a combination of two or more elements. The mineral Quartz, for example, is a combination of silicon and oxygen. Minerals can be recognized by observing their uniform chemical composition and crystallization pattern. Other examples of minerals include Fluorite, Opal, Dolomite, Sulfur, Ulexite, Chrysocolla, Magnetite, Epidote, Orthoclase, Pyrite, Talc, and Calcite.

A Rock is a combination of 2 or more minerals. Rocks are classified into three categories according to how they are formed:

1. Igneous rocks are formed when molten magma or lava cools and turns into a solid. Andesite once flowed from volcanos, while Obsidian was thrown from violent volcanic eruptions. Amazon Stone cooled and became rock before reaching the earth’s surface.

2. Sedimentary rocks formed when particles of sediment carried by wind, water, or ice piled up on top of each other in layers. The layers at the bottom are weighted down and cemented together by minerals—eventually, these layers of sediment turn to rock.

3. Metamorphic rocks are igneous or sedimentary rocks that have changed by recrystallizing due to heat and/or tremendous pressure deep below the earth’s surface. An example of metamorphic rock is Migmatite.