What texture do igneous rock have when magma cools?

Answer 1

It can be described as aphanitic. This just means that the rock has very small, hard to see crystals. The crystals do not have time to grow large when they are exposed to the air so they cool quickly and remain small. If water is added to the melt, the texture can be described as glassy (like obsidian).

Answer 2

If it's extrusive (cooled quickly above earth's surface, e.g. basalt) it will have a fine texture (small crystals).

If it's intrusive (cooled slowly below earth's surface, e.g. granite, rhyolite) it will have a coarse texture (large crystals).

Answer 3

Igneous rocks that cool slowly have a fine-grained or even glassy texture, while rocks that cool quickly have a coarse-grained texture. The texture of the rock can also be influenced by the mineral composition and crystal size of the rock.

Answer 4

It has a fine-grained texture when it cools rapidly and coarse-grained when cooled slowly.

Answer 5

The resultant texture is referred to as aphanitic, with grains too small to be seen without magnification.

Answer 6

When magma cools rapidly gaseous pockets and crystalline structure can not form. Such materials are known as glass and have a smooth surface, but fracture easily creating sharp jagged edges.

Answer 7

fine-grained

Answer 8

smooth and very glassy such as obsidian

Answer 9

Fine Grained Texture.