Geoscience Reference
In-Depth Information
Appendix A1: General
2
5
10
25
33
50
Figure A1.1
Chart to estimate percentage composition from area.
Table A1.1
Mohs' scale of hardness.
A metal hand lens provides
an excellent surface to test
for quartz. Simply scratch the
rock across the lens surface:
if it leaves a scratch on the
steel it is likely to contain
quartz. Note: For
sedimentary rocks it is
diagnostic of quartz, but in
crystalline rocks a few other
minerals will also scratch the
steel.
Mohs' hardness Reference mineral
Non-mineral example
1
Talc
2
Gypsum
(2.5)
-
Fingernail
3
Calcite
(3.5)
Copper coin*
4
Fluorite
5
Apatite
(5.5)
-
Window glass
6
Feldspar
(6.5)
-
Hardened steel (e.g. knife
blade)
7
Quartz
8
Topaz
9
Corundum
10
Diamond
*Note that many modern copper coins are actually copper coated steel and are
therefore harder.
