>>In this video we will discuss the properties
of minerals. One of the most important properties
is the hardness of the mineral. The hardness
of the mineral is based on the strength of
the bonds that occur in the mineral, and the
way we think of hardness is we have a scale.
It's called Mohs hardness scale, and it goes
from 1 to 10. As a point of reference, a knife,
some metal, has a hardness of 5. The mineral
gypsum--this is a piece of gypsum right here--has
a hardness of 2, and I can scratch it with
my fingernail. It's very soft. The mineral
talc, which is also very soft, is number 1
on the Mohs hardness scale. Quartz has a hardness
of 7. So you will not be able to scratch quartz
with metal, but in fact, quartz will scratch
metal. And what's the hardest mineral? That
would be diamond, and I don't have an example
of diamond for you to see right now. Another
mineral property is called the specific gravity.
The specific gravity is like the weight of
the mineral, and let me illustrate that here.
I have two minerals. This is galena, which
is lead. It's got lead in it. And this halite,
which is salt. They're about the same size.
Which one do you think is heavier? Galena
is a lot heavier. It has a higher specific
gravity. Another mineral property is the shape,
the crystal faces, and we talked about that
in the intro video. Here's quartz again, and
it has characteristic crystal shapes. That's
diagnostic of the mineral quartz. This pattern
is diagnostic. Another characteristic is called
cleavage. Some minerals break where there
are weak bonds. Here's mica, which is a good
example, illustrates cleavage. Remember mica
has a layered structure. Well, how does the
cleavage occur? It occurs between the sheets.
There's weakness there, so you're able to
break them apart. That's called the cleavage.
Different minerals have different types of
cleavage. Another property is color. There
are different colors associated with different
elements and impurities within the minerals.
For example, these minerals are both mica.
This is muscovite, and this is biotite--black
biotite, brownish or clear-ish muscovite.
Another property is taste. You lick a rock
or a mineral and find out sometimes what it
is. It's obvious what this is: it's halite
or salt. And finally another property of minerals
is their magnetic behavior. For example, I
have two samples here, and they're attracted
to each other, magnetite and hematite. They
also make some fun noises when you play with
them. These are the mineral properties.
