In: Physics
Compare and contrast the following pairs of rocks and explain what is the same and different, and why.
(a) Granite and Rhyolite
(b) Rhyolite and Basalt
(c) Granite and granitic gneiss
(d) Limestone and marble
(a)Granite is different from Rhyolite as it is very hard,
granular, crystalline and composed mainly of mica, quartz, and
feldspar. It is commonly used as a building stone. They are
plutonic meaning they are formed by solidification of lava under
the ground.
On the other hand, Rhyolite is fine-grained which is rich in
silica.
They are similar as both are igneous rocks formed by solidification
of volcanic lava. They are both durable and hard.
(b)Basalt is also a volcanic igneous rock like Rhyolite and formed
from the rapid cooling of the basaltic lava exposed at or very near
the surface of earth. Basalt is not water-resistant compared to
Granite and Rhyolite.
(c)Granite is Igneous whereas Granitic Gneiss is a metamorphic rock meaning it is formed by metamorphic processes from pre-existing formations that were originally granite. Gneiss is harder than Granite because it is metamorphosed. Gneiss also has a glittery appearance.
(d) Marble is a metamorphic rock formed from limestone which is
a sedimentary rock. Limestone is soft rock compared to marble which
is harder. Both are similar to the fact that they have a similar
composition of carbonates.