Rock, Baby, Rock

Which of the following describes a rock?

I. Solid

II. Heavy

III. Naturally occurring

IV. Aggregate of minerals

• A. I, II, and III

• B. I, III, and IV

• C. I, II, and IV

• D. II, III, and IV

Answer explanation

Not all rocks are heavy. Some are lightweight due to their spongy structure. One example is pumice.

Which of the following is a classification of sedimentary rock?

• A. intrusive rock

• B. foliated rock

• C. chemical rock

• D. non-foliated rock

Answer explanation

Chemical rock is formed when dissolved materials precipitate from the solution. An example of this is iron ore.

Which of the following statement is NOT TRUE about metamorphic rocks?

• A. It is formed when subjected to high heat and pressure.

• B. It is formed from plant and animal debris.

• C. Schist, phyllite, and gneiss are examples of sedimentary rocks.

• D. Foliated and non-foliated are classifications of sedimentary rocks.

Answer explanation

Metamorphic rock forms from existing rock types called “parent rock” in the process called metamorphism, which means a change in form.

Angela found a rock sample with a crystal white appearance which according to her friend was halite – a rock salt. What type of rock did she find?

• A. clastic rock

• B. organic rock

• C. chemical rock

• D. metamorphic rock

Answer explanation

Rock salt is one example of chemical sedimentary rock.

When the magma solidifies on the surface of the Earth, what possible igneous rock may be formed?

• A. scoria

• B. gabbro

• C. granite

• D. peridotite

Answer explanation

Scoria forms when magma containing abundant dissolved gas flows from a volcano or is blown out during an eruption. As the molten rock emerges from the Earth, the pressure upon it is reduced and the dissolved gas starts to escape in the form of bubbles.

Obsidian is a rock formed through fast solidification in exposure to air when a volcano erupts. What type of rock is obsidian?

• A. extrusive igneous rock

• B. extensive igneous rock

• C. intrusive igneous rock

• D. intensive igneous rock

Answer explanation

Obsidian was used to make knives, arrowheads, spear points, scrapers, and many other weapons and tools.

Which type of rock contains plants’ and animals’ remains?

• A. clastic rock

• B. foliated rock

• C. organic rock

• D. chemical rock

Answer explanation

Coquina is a type of organic rock composed of calcium carbonate shells, shell fragments, and other sand-sized fossil debris.

Which of the following statements is NOT TRUE about igneous rocks?

• A. It formed crystals.

• B. It is formed from magma.

• C. It can become glassy in appearance.

• D. It can be formed from an existing rock.

Which group of rocks formed from a precipitate of dissolved materials?

• A. clastic rock

• B. foliated rock

• C. organic rock

• D. chemical rock

Despite intense heat and pressure, non-foliated rocks did not form bands. Which of the following rocks is non-foliate?

• A. slate

• B. gneiss

• C. marble

• D. phyllite