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Minerals

A mineral is a naturally occurring substance with a constant chemical composition and range of physical properties.

There are about 3000 known minerals! Many are rare. Others are minor variations on a main mineral. Most of us will be able to get by with recognising the 20 commonest minerals.

Minerals are important in their own right,
'because they are there', and
because they have a wide range of uses
in industry and commerce. 		Sulphur

Minerals are the building blocks of rocks. In order to understand rocks, a good knowledge of minerals is essential. Certain minerals are associated with certain rock types;
the occurrence of minerals helps to determine the origin of both rock and mineral.


Being chemicals, minerals may be identified
by the usual range of analytical tests used
in the chemistry lab.
In the field, however, these tests are not
available and other more convenient, although often
less precise, tests can be employed for the
identification of minerals in hand specimen.

 Calcite

In many instances, it is not necessary to make a full list of properties of the mineral being identified.
With experience, a small number of observations (just one alone is too small a number!) may be enough to give a correct quick identification.

 Gypsum

The main minerals in rocks belong to the chemical group of the silicates made of silicon and oxygen, two of the most common elements in the Crust.


Silicates include
  • quartz
  • the feldspar family
  • the mica family
  • the hornblende family
  • the augite family
  • the olivine family
 Quartz

The physical properties of silicates depend on the

  • metallic elements which combine with the silicon and oxygen
  • arrangement of the atomic structure

Patterns can be established between the chemical composition, the atomic structure, the physical properties and the occurrence of these minerals.

When identifying minerals, a reference list of the properties of each mineral is needed - all 3000 of them! - so that a match may be made. Here, we will confine the list to the common minerals likely to be met in 'everyday' Geology in the field.

For convenience, the minerals are divided into three groupings:

Olivine

Fluorite

Haematite

The Study Topics
  • Introduction to Minerals
  • Identification of Hand Specimens
  • Quick Identification of Minerals
  • Properties of Silicates
  • Silicate Minerals
  • Chemical Minerals
  • Ore Minerals
are included in the Geopix "Minerals" Study Guide. The Guide also contains a selection of 40 multiple choice questions (with answers!) which help to test understanding of Minerals.

To order the "Minerals" Study Guide please visit the Geopix Online Store