Earth Materials

Investigation 3

Calcite Quest

Part 1 – Detecting Calcite

For the Teacher – Getting Ready

Put a sample of each rock on the rock identification sheet for students to refer to.

Pour vinegar into cups at the groups’ tables so students don’t have to carry full cups.

Label four half-liter containers with basalt, limestone, marble, and sandstone.

A fifth half-liter container will be unlabeled and contain small calcite samples.

For the Teacher – Getting ReadyStudent Materials

1 FOSS tray 5 Vials, 12-dr. (no caps) 1 Syringe Rock Samples

basalt, limestone, marble, sandstone, calcite 2 hand lenses 5 sticky notes

For the Teacher – Getting ReadyClass Materials

5 ½ liter containers 4 sticky notes 8 plastic cups vinegar, white paper towels Rock reference set Rock Identification Sheet Assessment Chart

What We Will Learn

Rocks are made of minerals.

Calcite is one of the most common minerals on Earth.

Putting acid on a rock is a tool geologists use to identify calcite.

Science Vocabulary

Basalt, limestone, marble, and sandstone are all rocks.

Calcite is a mineral.

Vinegar is an acid that can be used to test for calcite.

Detecting Calcite

How can we tell if one of the ingredients in a rock is the mineral calcite?

We are going to investigate these rocks looking for calcite: basalt limestone marble sandstone

Geological Study – 10 minutes

What is the first thing a geologist would do if he had four new rocks to study?

Yes, record observations. Materials Getters – get the rock samples and

hand lenses. Record your observations of the rock samples

on page 10 in your Earth Materials Notebook.

Reporters - Share Observations5 minutes

What is the difference between a rock and a mineral?

A rock is made up of many minerals. A mineral is made up of only one material. Rocks are made of many ingredients;

minerals are the ingredients in rocks. The basalt, limestone, sandstone, and marble

are all rocks.

New Material

Next you will get a sample of one of the minerals you used in the Scratch Test.

Materials Getters please get a sample of the material in the unlabeled container.

Can you name the material? You may use pages 8 and 9 of your Earth

Materials Notebook to help you. Yes, this is calcite.

Calcite

Your sample is the mineral calcite. This is one of the most common minerals on

Earth’s surface. Calcite is an ingredient in a number of

different kinds of rocks. The first four earth materials you observed

today are rocks. Let’s see if the mineral, calcite, is an

ingredient in any of these four rocks.

Calcite’s Unique Property

Calcite has a property that no other mineral has.

It reacts with cold acid. A field geologist often carries a small bottle of

hydrochloric acid to test rocks for calcite. Because hydrochloric acid is dangerous, we

will test rocks for calcite with a less concentrated acid, vinegar.

Procedure

1. Put the calcite sample in a vial.

2. Carefully add vinegar to the vial with the calcite.

3. Observe and record what happens on page 11 of the Earth Materials Notebook.

Getters get an empty cup and a vial. I will give each group some vinegar. Managers should fill the vial to about 1 cm

from the top.

Observations

Record your observations on page 11 of your Earth Materials Notebook.

From the observations you made earlier, which of the rocks do you think might have calcite as an ingredient?

There is no way to tell just by observing. What could you do to find out for sure if there

is calcite in any of these rocks? Yes, we can put them in vinegar and watch

for bubbles.

Bubbles

You will see two different kinds of bubbles. The bubbles from the calcite and acid

reaction are continuous and tiny, and form strings.

Air-pocket bubbles are bigger and not continuous.

Air-pocket bubbles may cling to the surface of the rock for a time before ascending.

Calcite Quest

Materials Getters get 1 FOSS tray and four vials. I will give you the vinegar.

Each student will put one of the four vials into a corner socket in the FOSS tray.

Each student will put one rock in a vial. Be sure to keep the rock label with the vial.

Each student will add vinegar to one of the vials until it is about 1 cm. from the top.

Record your observations on page 11.

Reporters – Share Observations

Which rocks do you think contain calcite?

Put a check next to the rocks that you think contain calcite.

We may need to do another test to be sure which rocks contain calcite.

Further Tests

We will let the vials sit overnight and then observe them for further clues.

Identify your tray with a sticky note.

Materials collectors will VERY CAREFULLY carry the trays to me for stacking on the window sill.

Content/Inquiry

Why are we testing for calcite in several rocks?

Calcite is one of the most common minerals on Earth.

Why use vinegar to test for calcite? Calcite is the only mineral that bubbles when

it comes in contact with cold acid.

What We Learned

Rocks are made of minerals.

Calcite is one of the most common minerals on Earth.

Putting acid on a rock is a tool geologists use to identify calcite.

Literature Connection

Old Man and the Rock: A Native American Tale