1. The word igneous is derived from the Latin word for
ignis or ignus.
2. Igneous rocks are commonly found in the
and
the Earth, specifically in divergent boundaries,
convergent boundaries, subduction zones and hotspots.
3. Igneous rocks are formed through the process of
and
of molten rocks; magma and lava.
4. When hot, molten rocks reach the surface of the earth, they undergo changes in
and
causing
them to
and
5. In tems of formation, igneous rocks can be classified into two;
and
rocks.
6. Intrusive rocks are formed solidified
while extrusive rocks are formed from solidified
7. Intrusive rocks cool
while extrusive rocks cool
8. Intrusive rocks have
grains and crystals while extrusive rocks have
grains and crystals.
9. Examples of intrusive rocks are
and
10. Examples of extrusive rocks are
and
11. Igneous rocks can also be classified according to their composition. They are composed of
12. If there is
of silica in the magma, its minerals will precipitate.
13. If there is
of silica in the magma, its minerals will not precipitate and will not be present in the igneous rocks
14. There are four classifications of igneous rocks based on silica content;
an
15.
has the highest amount of silica while
has the lowest.
16.
is the most viscous while
is the least.
17.
has the darkest color while
has the lightest
18.
is the densest while
is the lightest
.
19
is exposed to the highest temperature while is exposed to the lowest temperature.
20. The higher the silica content is, the
the color is and the
the silica content is, the darker the col
IS.​