TYPES OF ROCKS

What process is involved in the formation of igneous rocks?

• solidification of magma

• melting of crystals

• deformation of minerals

• compaction of sediments

Which type of igneous rock is formed when magma erupts and solidifies on the Earth’s surface resulting to the formation of very fine-grained crystals?

• plutonic

• porphyritic

• phaneritic

• volcanic

Which of the following distinguishes igneous rocks from other rock types?

• presence of layers

• crystalline appearance

• occurrence of deformation

• manifestation of released gas

An unknown rock, by inspection using hand lens, was seen to have abundant amounts of amphibole, sodium-rich and calcium-rich plagioclase with minor amounts of biotite. Given the composition, what is the proper name for the said rock?

• andesite

• diorite

• granite

• rhyolite

A pyroclastic rock is said to be comprised mainly of lapilli. What do you expect to observe in the said rock?

• The sizes of its pyroclast is greater than 64 mm.

• It has an observable intergrowth of crystals.

• The dominant pyroclast has diameters of 2 to 64 mm.

• It has abundant amount of volcanic glass.

Which of the following is a biochemical sedimentary rock?

• chalk

• travertine

• chert

• gypsum

Which of the following rocks will feel smoothest in your hand?

• conglomerate

• sandstone

• siltstone

• shale

How would you describe the depositional environment of a detrital rock if it is composed of well-sorted, coarse and rounded clasts?

• The sediments were carried by a high-energy current at a small distance from the source rock.

• The sediments were carried by a high-energy current at a large distance from the source rock.

• The sediments were carried by a low-energy current at a large distance from the source rock.

• The sediments were carried by a low-energy current at a small distance from the source rock.

By referring to the figure below, what is the proper name for the rock, and what binds the sediments together?

• sandstone; calcite, silt and clay

• sandstone; silt and clay

• siltstone; silt and clay

• siltstone; calcite cement only

An unknown sedimentary rock is said to be comprised mainly of very fine crystals of quartz and occurs as a light-colored rock. Given the said information, what would be the proper name for the rock?

• chert

• sandstone

• limestone

• bituminous coal