Author Question: True or False: Almost all natural rocks are consolidated aggregates of minerals. Indicate whether ... (Read 66 times)

jayhills49 · **on:** Jul 16, 2018

True or False: Almost all natural rocks are consolidated aggregates of minerals.

Indicate whether this statement is true or false.

Question 2

You are given two igneous rock samples; one is said to be an intrusive (plutonic) rock and the other an extrusive (volcanic) rock. How can you tell which is which?

What will be an ideal response?

sultana.d · **Reply #1 on:** Jul 16, 2018

Answer to Question 1

Answer: TRUE

Answer to Question 2

Answer: Fast magma solidification usually produces small crystals, while slower crystallization forms larger crystals. The generally fine-grained rocks result from rapid cooling following eruptions from volcanoes. The coarser rocks form from the slow solidification of magma beneath Earth's surface. So, an extrusive rock would be fine-grained with small crystals, while an intrusive rock would be coarse with larger crystals. Also, the accumulation of lava flows and ash deposits produces layers, while plutonic rocks rarely accumulate in layers.