Mohs Hardness, Another tool for Id'ing your finds. Options

[CP]

Mohs scale of hardness is a great tool to help Id stuff we all find.

Lets have a look at what that is and how we can use it in the field.
Also we will compare Mohs scale to "absolute" hardness which gives us more of an idea how much each hardness differs......you will be suprised.

Here's some info about Mohs from Wikipedia's pages....

The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science. Mohs based the scale on ten minerals that are all readily available. As the hardest known naturally occurring substance, diamond is at the top of the scale. The hardness of a material is measured against the scale by finding the hardest material that the given material can scratch, and/or the softest material that can scratch the given material
For example, if some material is scratched by apatite but not by fluorite, its hardness on the Mohs scale would fall between 4 and 5.

Now.....Onto common test materials used.........
On the Mohs scale, a pencil lead has a hardness of - 1
a fingernail has hardness - 2.5
a copper penny, about - 3.5
a knife blade - 5.5
window glass - 5.5
steel file - 6.5
Using these ordinary materials of known hardness can be a simple way to approximate the position of a mineral on the scale.

And the Mohs Scale itself along side what is called "absolute" hardness.

Mohs..............Mineral....................Absolute
1----------------------Talc--------------------------1
2---------------------Gypsum----------------------2
3----------------------Calcite-----------------------9
4----------------------Fluorite----------------------21
5----------------------Apatite----------------------48
6-------------Orthoclase/Feldspar-----------72
7----------------------Quartz----------------------100
8----------------------Topaz-----------------------200
9---------------------Corundum-------------------400
10--------------------Diamond--------------------1500


You can view the page at Wikipedia-Mohs hardness for lots more information on this.

CP

[Denise]

Here is a chart that we have. It varies a bit from the Wiki page with the hardness scale but I think this one is correct.
Please correct me if I'm wrong.