Revised 11/2011

Rock Identification Lab

Introduction:

A rock is any naturally formed solid on Earth or in any part of the universe. Most rocks are

mixtures of minerals, organic materials, glasses, and fragments of other rocks. Yet, with the

possibility of many different rock formations, there are only 3 main categories: sedimentary,

igneous, and metamorphic. Rocks are categorized by how they were formed and what they were

made from.

Materials and Methods:

1. Create a chart with the headings as shown below and six rows numbered 1-6.

2. Using your chart, a magnifying glass, and your Earth Science Reference Tables, determine

the classification of the 6 given rock samples.

3. For each sample, include two reasons for your classification.

4. Finally, after classifying ALL 6 rock samples, answer the conclusion questions below.

Rock ID #

Rock Type

ROCK NAME Reasons for

Classification

Conclusion Questions:

Igneous Rocks:

1) How is the size of the mineral grains affected by the rate at which the rock cooled?

2) In general, how does the density of a light colored igneous rock differ from that of a

dark colored igneous rock?

Sedimentary Rocks:

3) Describe the difference between a crystalline and a bioclastic sedimentary rock.

4) What are the size ranges (dimensions) for the following particle sizes?

a) Cobble, b) Pebble, c) Sand. Also, list an example of each of these sizes.

Metamorphic Rocks:

5) Why do minerals in regional metamorphic rocks often arrange in different colored

layers? (Hint: Use your answer to conclusion question #2 to help.)

6) Why do you seldom find fossils in metamorphic rock?