Practice Questions Igneous Rocks (Page 3 of 4) in pdf

Practice Questions Igneous Rocks Page 3

10. The diagrams below show the crystals of four different rocks viewed through the same hand lens. Which

crystals most likely formed from molten material that cooled and solidified most rapidly?

11. An extrusive igneous rock with a mineral composition

of 35% quartz, 35% potassium feldspar, 15%

plagioclase feldspar, 10% biotite, and 5% amphibole is

called

A) rhyolite

B) granite

C) gabbro

D) basaltic glass

12. Which process is necessary for the formation of igneous

rocks?

A) erosion

B) deposition

C) solidification

D) metamorphism

13. Which characteristic provides the best evidence that

obsidian rock formed in an extrusive environment?

A) layers of rounded fragments

B) distorted bands of large mineral crystals

C) noncrystalline glassy texture

D) mineral cement between grains

14. Which two igneous rocks could have the same mineral

composition?

A) rhyolite and diorite

B) pumice and scoria

C) peridotite and andesite

D) gabbro and basalt

15. Which relative concentrations of elements are found in

a felsic rock?

A) a high concentration of aluminum and a low

concentration of iron

B) a high concentration of iron and a low

concentration of aluminum

C) a high concentration of magnesium and a low

concentration of iron

D) a high concentration of magnesium and a low

concentration of aluminum

Practice Questions Igneous Rocks Page 3