the above picture shows a type of igneous rock called obsidian. why is the top rock so shiny and smoother…
the above picture shows a type of igneous rock called obsidian. why is the top rock so shiny and smoother than the others? a. it was formed when lava cooled very quickly. b. it was formed inside a volcano. c. years of weathering has made it smooth. d. it is made of sand - sized pieces of other rocks.
Answer
Brief Explanations:
Obsidian is an igneous rock formed from rapidly - cooled lava. Rapid cooling prevents the formation of large crystals, resulting in a smooth, glassy texture. Option B only mentions formation inside a volcano but not the key factor of rapid cooling. Option C, weathering would not typically create such a smooth and shiny surface characteristic of obsidian. Option D describes sedimentary rock features, not obsidian.
Answer:
A. It was formed when lava cooled very quickly.