Natural glass such as obsidian forms when ____. A)magma cools too ...

[rlane42]

Natural glass such as obsidian forms when ____.
 A)magma cools too rapidly for crystals to form
 B)pegmatite melts, moves to Earth's surface and ,re-forms
 C)magma cools too slowly for crystals to form
 D)magma has a very low silica content
 E)gas escapes through lava

Question 2

Stromatolites are the product of organic activity.
  Indicate whether the statement is true or false

[Smiles0805]

Answer to Question 1

A

Answer to Question 2

True

[rlane42]

TYSM

[bulacsom]

Gracias!