Question

Which best explains why this extrusive volcanic rock does not have visible crystals

Answer 1

The options are:

A. It is homogeneous and composed of a soft mineral.

B.  It does not contain atoms of any Earth minerals.

C.  It cooled down before large crystals could form.

D.  It wasn’t exposed to friction during its formation.

But the answer is

C.  It cooled down before large crystals could form.

I took the Plato test and this is what I learned and what most people seem to pick.

Answer 2

Extrusive volcanic rocks are formed on the surface of the earth and cool relatively quickly from lava erupted from a volcano. The rapid cooling of lava on the surface does not allow for visible crystals to form. The crystals are minute and most can only be seen under a microscope. Basalt is an example of an extrusive igneous rock.

Intrusive igneous rocks are formed when magma cools within the crust. This magma cools slowly and so crystals develop in these rocks. Granite is an intrusive igneous rock.