Rocks & Minerals Fact Sheet
Organisation of Rocks
Minerals
Much like atoms to matter and cells to living things, minerals are the building blocks of rocks.
A mineral is a natural substance with a crystal structure, such as quartz, emerald or diamond.
All rocks are made up of one or more minerals.
_____________ is a rock made up of one mineral, called ____________________.
______________ is a rock made of many minerals.
Five properties of minerals include




Explain why you can’t assume these are two different minerals.
Feldspar scratches calcite. Calcite scratches muscovite.
Determine the correct order of the minerals from softest to hardest.
Describe what lustre is.
Streak –
When a mineral is ground up to form a powder, it often has a different colour. Geologists test
this by scraping the mineral on a white ceramic plate. The colour of the trail of powder left
behind is the mineral's streak.
This property can be used to help identify the mineral.
Only minerals that are softer than the ceramic plate leave behind a streak. Minerals that are
harder than 5.5, such as quartz and feldspar, do not have a streak.
Select which item geologists use to test a mineral's streak.
a)
b)
c)
d)
Glass
White ceramic plate
Copper coin
Quartz
Cleavage Minerals break at specific points depending on their atomic structure. When a mineral
breaks along a plane of weakness and leaves a flat surface, this is called a cleavage
plane. These surfaces are typically smooth and reflect light evenly.
Not all minerals have cleavage planes.
Some minerals just fracture in random
locations.