- Minerals are usually formed
- Shape of minerals can change
from environmental factors such as erosion and weathering (you will
learn more about these soon)
- Shapes of crystals found in
minerals are used to identify them
Color and Streak
- Color is one of the most commonly
used properties to identify minerals
- However, color can change due
to weathering (i.e. rusting of iron)
- Breaking a sample of a mineral
will help to reveal its true color
- The easiest way to do this
is by way of a streak test, in which a sample of the mineral is scraped
over a white, unglazed tile called a streak plate.
- The colour of the powder mark
that is left on the tile is usually a good clue to the mineral's identity.
- Minerals vary a great deal
in hardness, but scientists are able to determine ranges of hardness
by way of a list called Moh's
- The scale ranges from the softest
mineral (talc) to the very hardest (diamond).
- If two minerals are scratched
across each other, the one that leaves a streak will always be the
softest of the two.
- Luster describes how a mineral
or object reflects light.
- It can also be described as
glassy, waxy, oily, shiny and metallic.
Cleavage and Fracture
- If a mineral can be split or
broken on a flat plane then it has cleavage.
- Minerals can split in one or
- If a mineral doesn't split
on flat planes or shatters easily than it is said to have fracture.