Answer:
on the surface rapidly
Explanation:
Obsidian glassy texture indicates that the rock formed on the surface rapidly.
Like every other magma, the condition of the environment determines how the magma cools and solidifies.
- When magma cools rapidly, nucleation centers will be difficult to come- by ..
- At nucleation centers, minerals aggregates and grows to form different grain sizes.
- When rapid cooling occurs, not enough time is given for the aggregation around the nucleus.
- This leaves a rock mass that is finely grained.
