An introduction to geology
An introduction to geology

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

An introduction to geology

1.4 Identifying rock textures

Take a look at a hand specimen and a thin section of each of these rocks:

(open the links in a new window so you can come back to this page more easily)

When you've taken a good look at the rocks, complete the quiz below.

Activity 1.2 Rock specimen quiz

Timing: Allow about 10 minutes

You may take as many attempts as you wish to answer each question, and you can skip questions and come back to them later if you wish.

1. Select all the correct observations of each textural feature of gneiss:

a. 

Interlocking crystals


b. 

Rounded grains


c. 

Randomly oriented crystals/grains


d. 

Crystals/grains showing banding or alignment in one preferred direction


The correct answers are a and d.

2. Select all the correct observations of each textural feature of conglomerate:

a. 

Interlocking crystals


b. 

Rounded grains


c. 

Randomly oriented crystals/grains


d. 

Crystals/grains showing banding or alignment in one preferred direction


The correct answers are b and c.

3. Select all the correct observations of each textural feature of gabbro:

a. 

Interlocking crystals


b. 

Rounded grains


c. 

Randomly oriented crystals/grains


d. 

Crystals/grains showing banding or alignment in one preferred direction


The correct answers are a and c.

4. Gneiss has a banded crystalline texture and is therefore …

a. 

sedimentary


b. 

metamorphic


c. 

igneous


The correct answer is b.

5. Conglomerate has a fragmental texture and is therefore …

a. 

igneous


b. 

metamorphic


c. 

sedimentary


The correct answer is c.

6. Gabbro has a crystalline texture and lacks mineral alignment or banding and is therefore …

a. 

sedimentary


b. 

igneous


c. 

metamorphic


The correct answer is b.

OUFL_1009

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371