Rocks And Minerals Quiz 1

1. A specimen exhibits strong birefringence, excellent cleavage in three directions, and effervesces when tested with HCl. These are distinguishing characteristics of...

Calcite

Halite

Muscovite

Pyrite

You knew that!

Explanation

You knew that!

2. Which of the following minerals has NO cleavage, and conchoidal fracture?

Muscovite

Quartz

Calcite

Halite

Think about quartz's crystal structure... no planes of weakness...

Explanation

Think about quartz's crystal structure... no planes of weakness...

3. Albite is an end member of which mineral group?

Orthoclase feldspar

Pyroxene

Olivine

Plagioclase feldspar

Not A.

Explanation

Not A.

4. Which of the following minerals is the main constituent of Earth's mantle?

Olivine

Biotite

Feldspar

Quartz

Magnetite

The mantle is primarily composed of peridotite, an ultramafic igneous rock rich in olivine. Peridotite gets its name from its main mineral constituent, peridot, which is gem-quality forsterite, and forsterite is the Mg end member of the olivine group.

Explanation

The mantle is primarily composed of peridotite, an ultramafic igneous rock rich in olivine. Peridotite gets its name from its main mineral constituent, peridot, which is gem-quality forsterite, and forsterite is the Mg end member of the olivine group.

5. Which of the following properties would you best use to distinguish halite from calcite?

Streak

Color and luster

Crystal system and cleavage

Taste

Well, you could lick your specimen, but nobody would recommend that.

Explanation

Well, you could lick your specimen, but nobody would recommend that.

6. Which of the following minerals is an ore of mercury associated with volcanic activity?

Hematite

Cinnabar

Galena

Epsomite

Probably all you need to know about cinnabar.

Explanation

Probably all you need to know about cinnabar.

7. What is considered "low" silica content in a magma melt?

About 50%

About 70%

About 20%

About 95%

You'll never find a melt that's more than about 78% silica. Melts that are less than 45% silica are considered ultramafic - that's very low silica content.

Explanation

You'll never find a melt that's more than about 78% silica. Melts that are less than 45% silica are considered ultramafic - that's very low silica content.

8. A mineral will scratch apatite, and is scratched by topaz. Which of the following might it be?

Olivine

Fluorite

Corundum

Bornite

Olivine again!

Explanation

Olivine again!

9. Which of the following sets of minerals are polymorphs of each other?

Quartz and corundum

Orthoclase and plagioclase

Calcite and dolomite

Calcite and aragonite

Biotite and muscovite

Aragonite actually isn't stable under normal conditions, so you'll never find it in surface rocks older than about 50 million years! Still, it's a common collector's specimen.

Explanation

Aragonite actually isn't stable under normal conditions, so you'll never find it in surface rocks older than about 50 million years! Still, it's a common collector's specimen.

10. Which of the native metals gold, copper and silver is the best conductor (1)? Which is most malleable (2)?

(1) silver and (2) copper

(1) copper and (2) copper

(1) copper and (2) gold

(1) gold and (2) gold

(1) silver and (2) gold

Silver is the best conductor of electricity among the native metals gold, copper, and silver. This is because silver has the highest electrical conductivity of any metal. Gold is the most malleable among the three metals. It can be easily hammered into thin sheets without breaking.

Explanation

Silver is the best conductor of electricity among the native metals gold, copper, and silver. This is because silver has the highest electrical conductivity of any metal. Gold is the most malleable among the three metals. It can be easily hammered into thin sheets without breaking.