Question

How are granite and rhyolite the same, and do they differ?

Answer 1

Hint: Rhyolite and granite have similar composition. The difference between them is that rhyolite is an intrusive igneous rock whereas granite is an extrusive igneous rock. 0ne is formed within the earth's crust, another is formed near or on the earth’s surface.

Complete answer: The term igneous comes from a Latin word 'Ignis' meaning fire. Igneous rocks are formed from cooling down of magma and lava.
The composition of igneous rocks can be divided into four categories. These categories are on the basis of the amount of silica the rock contains. These are: acidic, intermediate, basic and ultramafic. Rhyolite and Granite are the most common types of acidic rock. They have similar compositions.
Granite is formed when magma cools down deep inside the earth crust. It is an intrusive igneous rock. It has large crystals and is thus called coarse-grained.
Rhyolite is closely related to granite. It differs by granite because it has much finer crystals. These crystals cannot be seen through naked eyes because the crystals are so small in size. Unlike granite, it is formed when lava cools down on or near the earth's surface. It is an extrusive igneous rock. It is formed by rapid cooling giving it a glassy appearance. Rhyolite consists of minerals like quartz, feldspar, mica and hornblende.

Note: There’s a difference between magma and lava. The molten rock inside the earth’s crust is known as magma. When this molten rock comes out on earth's surface it is known as lava. These concepts can come in handy when explaining the difference between intrusive igneous rock and extrusive igneous rock.