SK Curriculum RM4.1, RM4.2
SCI – ‘Two-eyed Moh!’
Where did they come from, where will they go?
Rocks are made out of one or more minerals. A
mineral is a component of a rock that has a
uniform chemical composition. For example,
table salt is a mineral that contains sodium and
chloride.
Geologists use careful observation of rock
samples to determine what minerals, and what
chemicals, they contain. They look at the
mineral’s colour, luster (shininess), the way that
it breaks, and where it is found.
One really useful clue to mineral composition is
a rock's hardness.
Friedrich Moh was a German scientist who, in
1812, devised a scale to relate the relative
hardness of rocks to the minerals that they
contain. This is called 'Moh's hardness scale'.
For many thousands of years people all around
the world were already using the relative
hardness of rocks to identify them, and
determine how they might be used. This hasn’t been named per-say, but goes well with Moh’s hardness scale – there are more than one
cultural ways of understanding and making sense of the property of hardness so we are calling this activity a ‘two-eyed’ scale
MATERIALS: an assortment of mineral samples with varying hardness, as well as a collection of rocks (students may gather these from the river
bank, a playground, other), glass plate, streak plate, nail, copper penny; aluminum foil, wooden skewers
RELATED MEDIA: Moh’s two-eyed harness scale; What tool is this? Slide show quiz
Activity part 1: ‘Moh’s hardness scale’
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Discuss, how do you know how hard something is? (note that it is different from friability
(or ease of breaking) – glass is hard but breaks easily)
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Conduct Moh’s hardness test on the mineral samples that you have available – sort them
in order from hardest to softest – can any of them be identified on this property alone?
These rock hardness activities were developed by ETAD 874 class (spring 2013) in consultation with
Wanuskewin Heritage Park and graduate student Bryce Stan, University of Saskatchewan
SK Curriculum RM4.1, RM4.2
Activity part 2: ‘Hardness and stone technologies’
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First Nations people used many rocks and minerals for different purposes – these include stone tools like arrowheads and axe heads,
as well as pigments made by crushing soft minerals (usually red-orange iron oxides) and mixing them with oils to make paint, and
medicinal purposes.
In many cases the hardness of mineral and rock resources determined their use
Compare the hardness of the found rock samples that you have to Moh’s hardness scale
Arrange your rocks in order of hardness
How would each be used?
What other properties of the rock would determine how they would be used (how they break=cleavage, luster=beauty, etc.)
Activity part 3: ‘Cold metalwork’
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The Dene in Northern Saskatchewan were some of the earliest metal workers in North America
They used a process called cold smelting - which means that they shaped and hammered copper into desired shapes (ornaments,
jewelry, knife hilts, etc.) using cold and heat but without melting the metal
The Dene are thought to have traded widely with tribes to the south, perhaps as far south as Arizona
They have a story that tells of how Copper was found, and the technique introduced to the Dene people by the Inuit near
Coppermine
We can practice cold smelting to make jewelry today
Give it a try making beads and other shaped ornaments by first pounding tin foil with your rocks to make it malleable, then shaping
it more carefully with skewers and nails
Here is an example of North American copper work:
These rock hardness activities were developed by ETAD 874 class (spring 2013) in consultation with
Wanuskewin Heritage Park and graduate student Bryce Stan, University of Saskatchewan