CHAPTER XXXI.
MINERALOGY AND CRYSTALLOGRAPHY.
THE MINERALS—CHARACTERISTICS—CRYSTALS AND THEIR FORMS—DESCRIPTIONS OF MINERALS.
Minerals are constituent parts of the earth. All parts of minerals are alike. There are simple minerals and mixed. The former are the true minerals, and are generally considered under the heading Mineralogy. The others constitute a branch of Geology, as they form aggregate masses, and as such compose a large portion of the earth. We must learn to distinguish minerals and crystals as inorganic forms of nature. In the animal and vegetable kingdoms we have forms which are possessed of organs of sight, smell, taste, and certain structures indispensable to their existence and development. But in minerals we have no such attributes. They are INORGANIC, and have a similar structure; a fragment will tell us the story as well as a block of the same mineral. These inorganic substances are possessed of certain attributes or characteristics. We find they have FORM. They have chemical properties, and they behave differently when exposed to light and electricity. They are generally solid. All the elements are found in the mineral kingdom, and a mineral may be an element itself, or a chemical combination of elements. These compounds are classed according as the combination is more or less simple. An alliance of two elements is termed a binary compound, of three a ternary compound, forming a base and an acid.
We have learnt from our chemistry paper that there are between sixty and seventy elementary bodies in nature. When we speak of “elements,” we do not mean to apply the popular and erroneous definition of the word. Earth, air, fire, and water are not elements; they are compounds, as we have seen. The list of elements has been given; we will now give the names of the more important minerals. We have no space for a detailed description, but in the British Museum the cases contain some hundreds, and the student will find them classified and described with the greatest care, and according to the arrangement of Berzelius.
Principal Minerals as arranged by Professor Ansted.
The above is the arrangement best suited for beginners.
Professor Nichol prefers the following arrangement:—