Minerals, Soil, and Fossils Study Guide

What is a rock?

A rock is a naturally formed solid made up of one or more minerals. Rocks can have many different colors! The colors represent the different minerals that make up the rock

What is a mineral?

A mineral is a solid object that is formed in nature and has never been alive. A mineral is made up of one mineral and is the same all the way through. They are normally the same color all the way through

How do I describe rocks and minerals?

Color, Hardness, Texture, and Luster

Color

Different kinds of rocks have different colors. The colors come from the minerals in the rock. Color is one of the easiest ways for a scientist to tell minerals apart!

Hardness

Hardness is the measure of how difficult it is for a mineral to be scratched. We test the hardness of rocks and minerals using a scratch test. Mohs Scale is a tool scientists use to tell the hardness of a mineral. Diamonds are the hardest mineral!

Texture

You can see or feel tiny pieces of minerals in rocks. These pieces are called grains. A rock’s texture is based on the size and shape of its grains. You can feel texture. We describe rocks texture as rough or smooth

Luster

What does your rock look like when the light hits it? Is it shiny,  sparkly, dull, or greasy?

What is Soil?

Soil is amix of tiny rocks and bits of dead plants and animals. There are three types of soil: Sand, Silt, and Clay

Sand

• Largest particles

• Does NOT hold water well

• Is not good for growing plants (does not hold water well)

• Gritty

Silt

• Medium Particles

• Holds some water

• Better than clay for planting, but still not the best

• When it is wet, it becomes very hard and tightly packed

• Fine/Smooth

Clay

• Smallest particles

• Holds water very well

• Is NOT good for planting

• Holds a bunch of water, but is hard for the roots to grow down into the clay

• Sticky

What is Loam?

A mixture of sand, silt, and clay

Loam (characteristics)

• Holds water well

• Good for growing, because it holds water well, and contains a lot of nutrients

• Rough

How does water and wind change rocks over time?

By weathering and erosion

Weathering

The breaking down of rocks into smaller pieces

Erosion

The movement of weathered rock and soil

Fossils

A trace or the remains of a living thing that died a long time ago. Fossils tell scientists about the plants and animals that lived on land and in water long ago. Scientists can learn information about extinct animals by studying fossils

How are fossils formed?

Trace fossils, molds, casts, and preserved remains (amber fossils)

For a fossil to form, an animal must die and be buried by mud, sand, or clay!

Trace Fossils

Marks that are left behind in the mud, when the mud hardens, then it becomes a trace fossil

Mold

A mold is the shape of the once living thing left in sediment when the rock formed. The living thing that made the mold break down, leaving only a cavity shaped like the plant/animal

Cast

A cast forms when mud or minerals later fills a mold. The cast has the actual shape of the living thing.

Amber Fossils (Preserved Remains)

Amber fossils are actual remains of an organism trapped in earth materials (such as tree sap) that hardens over time