RELATIVE SCALE OF HARDNESS
The hardness of a mineral is often defined by using
Moh's Scale of Relative
Hardness. This scale was
developed in 1822 by Friedrich Moh to measure the hardness of
minerals. The idea behind Moh's Scale was that minerals or
substances with a lower hardness could not scratch minerals or
substances with a greater hardness.
This is the softest of the minerals
and can easily be scratched with a fingernail. It is used in paint,
paper,and talcum powder. Soapstone consists mainly of talc.
This mineral can barely be scratched with a fingernail. It
is used for plaster of paris, wallboard, and interior plaster.
Alabaster is a fine-grained variety of gypsum.
You can barely scratch calcite with a copper penny.
Limestone and marble are varieties of calcite.
This mineral can easily be scratched with a knife blade. It
is a beautiful mineral occurring in many different colors and is
mainly used for making steel.
Can barely be scratched with a knife blade. Its
greatest use is as a source of phosphorus for common
This mineral cannot be scratched by a knife blade but it can
easily be scratched with window glass. It is found in most igneous
rocks, and is an essential component of crystalline rocks such as
granite, gabbro, and basalt.
This is the most common mineral and often the most
beautiful. It will easily mark steel and hard
glass. Quartz makes up the sand on our seashores and is found in
sandstone and quartzite. Some varieties of quartz are used as
gemstones. These include amethyst, bloodstone, crystal, flint, and
It is harder than other common materials and also highly
prized as a gem.
This mineral will scratch Topaz. Clear blue varieties make
the sapphire, and clear red varieties make the ruby. Corundum is
often used as an abrasive.
This is considered the hardest
mineral and will scratch corundum as well as all
minerals on this scale. The hardness of the diamond is greater than
any other known substance natural or artificial. Diamond is pure
carbon and highly prized as a gemstone.