Rocks are simply naturally occurring aggregates of minerals. Minerals are the building blocks of rocks. Ice is a mineral.
Minerals are naturally occurring homogeneous solid formed through geological processes; has a characteristic of
chemical composition; highly ordered atomic structure and has specific physical properties.
Igneous rocks are those made up of cool magma and are called as born of fire.
The silicate ion forms tetrahedral composed of a central silicon ion surrounded by 4 oxygen ions. The silicate ion is the
basic building block of all silicate mineral and 90% minerals are silicates
Quartz: The mineral class is silicates. The silicate class is tectosilicates. Quartz is common in ign, metam and sed rocks
Feldspars: The mineral class is silicates. The silicate class is tectosilicates. Quartz is common in ign, metam and sed rocks
MICAs: The mineral class is silicates. The silicate class is phyllosilicates. Quartz is common in ign and metam. It is also
found in makeup and car paint
Calcite: The mineral class is carbonates and it is common in sedimentary rocks. It glows in the dark and it will fizz in acid
Study table on page 9
How do we identify minerals?
Color – least accurate
Streak – color when mineral group to a fine powder on streak plate. Silicate minerals do not streak
Hardness – Diamond is the hardest and talc is the softest
Crystal shapes – eg: pyrite forms some well-shaped cubes
The rock cycle (how does the rock cycle relate to plate tectonics? How does the rock cycle related to natural hazards?)
Any type of rock can change into any other type of rock. Cooling magma provides igneous rocks. If these igneous rocks
When trying to understand we need to know the source (where is the material coming from), the process (how is it
formed) and product (what is formed)
Source – hot molten magma. When it freezes/solidifies, it produces igneous rocks. The magma is called a basaltic
magma. Basaltic is rich in iron and magnesium and ocean floor because the ocean floor is made up of it too. A’a is blocky
lava from cooler flows (it is painful to walk on it). Pahoehoe is ropy lava from hotter flows. Difference between magma
and lava – once magma comes out of the earth, we call it lava.
Igneous rocks can form from cooled magma either:
1) Extrusive (or volcanic) – at the earth’s surface. This cools quickly and forms fine crystals. The size of crystals indicates
how long it had to cool down.
2) Intrusive (or plutonic) – Magma cooled underground. This cools slowly and forms medium/large & coarse crystals
Interior of a volcano
Batholith is an enormous chamber holding large amount of magma. Magma comes out the volcanic pipe and exits the
volcano. Sills follows the layers of rocks that were there before whereas Dykes cut across those layers in some angle.
They both allow the flow of magma.
How do we classify igneous rocks?
1) Igneous rocks are classified by composition. Mafic are used to describe minerals that contain magnesium and iron.
Eg: Basalt is a mafic. On the other hand, felsic is rich light colored and light weight things such as silica. We use the
terms mafic, intermediate and f