Obsidian is an igneous rock with a glassy appearance and minimal crystal growth.What accounts for this?
A)Obsidian is an extrusive igneous rock that cooled rapidly on Earth surface,resulting in little crystal growth.
B)Obsidian is an intrusive igneous rock that cooled rapidly beneath Earthʹs surface,resulting in little crystal growth.
C)Obsidian is an intrusive igneous rock that cooled slowly beneath Earthʹs surface,resulting in little crystal growth.
D)Obsidian is an extrusive igneous rock that cooled very slowly on Earth surface,resulting in little crystal growth.

Question

Quizplus · Accepted Answer

Obsidian is formed from lava that cools rapidly on the surface of the Earth, which inhibits the growth of crystals. This rapid cooling prevents the minerals in the lava from forming a crystalline structure, resulting in a glassy appearance. Therefore, option A is the correct answer.

Obsidian Is an Igneous Rock with a Glassy Appearance and Minimal